ⓘ 13 (number)

13 (number)

ⓘ 13 (number)

13 is the natural number following 12 and preceding 14.

Strikingly folkloric aspects of the number 13 have been noted in various cultures around the world: one theory is that this is due to the cultures employing lunar-solar calendars. This can be witnessed, for example, in the "Twelve Days of Christmas" of Western European tradition.


1. In mathematics

The number 13 is:

  • the smallest number whose fourth power can be written as a sum of two consecutive square numbers 119 2 + 120 2.
  • a lucky number.
  • the sixth prime number.
  • equal to the sum of the squares of the digits of its own square in bases 4 and 83.
  • a happy number.
  • one of only three known Wilson primes.
  • a Fibonacci number.
  • the smallest emirp a prime that is a different prime when its digits are reversed.
  • the third centered square number.

Since 5 2 + 12 2 = 13 2, 5, 12, 13 forms a Pythagorean triple.

There are 13 Archimedean solids as normally counted, although some include the Elongated square gyrobicupola as a fourteenth.

A standard torus can be sliced into 13 pieces with just 3 plane cuts.

There are also 13 different ways for the three fastest horses in a horse race to finish, allowing for ties, a fact that can be expressed mathematically by 13 being the third ordered Bell number.


2. In languages


  • The Romance languages use different systems: In Italian, 11 is the first compound number undici, as in Romanian unsprezece, while in Spanish and Portuguese, the numbers up to and including 15 Spanish quince, Portuguese quinze, and in French up to and including 16 seize have their own names. This is also the case in most Slavic languages, Hindi-Urdu and other South Asian languages.
  • In all Germanic languages, 13 is the first compound number; the numbers 11 and 12 have their own names.


In Germany, according to an old tradition, 13 dreizehn, as the first compound number, was the first number written in digits; the numbers 0 null through 12 zwolf were spelled out. The Duden the German standard dictionary now calls this tradition which was actually never written down as an official rule outdated and no longer valid, but many writers still follow it.


3. In religion


Since beginning of the Nowruz tradition, the 13th day of each new Iranian year is called Sizdah Be-dar, a festival dedicated to pranks and spending time outdoors.


  • The Thirteen Classics is considered to be a part of the Chinese classics.

3.1. In religion Islam

In Shia Islam, 13 signifies the 13th day of the month of Rajab the Lunar calendar, which is the birth of Imam Ali. 13 also is a total of 1 Prophet and 12 Imams in the Islamic School of Thought. However, in Sunni Islam, the number 13 bears no symbolic significance.


3.2. In religion Christianity

The apparitions of the Virgin of Fatima in 1917 were claimed to occur on the 13th day of six consecutive months.

In Catholic devotional practice, the number thirteen is also associated with Saint Anthony of Padua, since his feast day falls on June 13. A traditional devotion called the Thirteen Tuesdays of St. Anthony involves praying to the saint every Tuesday over a period of thirteen weeks. Another devotion, St. Anthonys Chaplet, consists of thirteen decades of three beads each.


3.3. In religion Judaism

  • The number of principles of Jewish faith according to Maimonides.
  • According to Rabbinic commentary on the Torah, God has 13 Attributes of Mercy.
  • In Judaism, 13 signifies the age at which a boy matures and becomes a Bar Mitzvah, i.e., a full member of the Jewish faith counts as a member of Minyan.

3.4. In religion Zoroastrianism

Since beginning of the Nowruz tradition, the 13th day of each new Iranian year is called Sizdah Be-dar, a festival dedicated to pranks and spending time outdoors.


3.5. In religion Other

  • The Thirteen Classics is considered to be a part of the Chinese classics.

4.1. Lucky and unlucky Unlucky 13

The number 13 is considered an unlucky number in some countries. The end of the Mayan calendars 13th Baktun was superstitiously feared as a harbinger of the apocalyptic 2012 phenomenon. Fear of the number 13 has a specifically recognized phobia, triskaidekaphobia, a word coined in 1911. The superstitious sufferers of triskaidekaphobia try to avoid bad luck by keeping away from anything numbered or labelled thirteen. As a result, companies and manufacturers use another way of numbering or labelling to avoid the number, with hotels and tall buildings being conspicuous examples thirteenth floor. It is also considered unlucky to have thirteen guests at a table. Friday the 13th has been considered an unlucky day.

There are a number of theories as to why the number thirteen became associated with bad luck, but none of them have been accepted as likely.

  • A Repressed Lunar Cult: In ancient cultures, the number 13 represented femininity, because it corresponded to the number of lunar menstrual cycles in a year 13 x 28 = 364 days. The theory is that, as the solar calendar triumphed over the lunar, the number thirteen became anathema.
  • The Last Supper: At Jesus Christs last supper, there were thirteen people around the table, counting Christ and the twelve apostles. Some believe this is unlucky because one of those thirteen, Judas Iscariot, was the betrayer of Jesus Christ. From the 1890s, a number of English language sources relate the "unlucky" thirteen to an idea that at the Last Supper, Judas, the disciple who betrayed Jesus, was the 13th to sit at the table.
  • Full Moons: A year with 13 full moons instead of 12 posed problems for the monks in charge of the calendars. "This was considered a very unfortunate circumstance, especially by the monks who had charge of the calendar of thirteen months for that year, and it upset the regular arrangement of church festivals. For this reason, thirteen came to be considered an unlucky number." However, a typical century has about 37 years that have 13 full moons, compared to 63 years with 12 full moons, and typically every third or fourth year has 13 full moons.
  • Knights Templar: On Friday 13 October 1307, King Philip IV of France ordered the arrest of the Knights Templar, and most of the knights were tortured and killed.
  • Hammurabis Code: There is a myth that the earliest reference to thirteen being unlucky or evil is in the Babylonian Code of Hammurabi circa 1780 BC, where the thirteenth law is said to be omitted. In fact, the original Code of Hammurabi has no numeration. The translation by L.W. King 1910, edited by Richard Hooker, omitted one article: If the seller have gone to his fate i. e., have died, the purchaser shall recover damages in said case fivefold from the estate of the seller. Other translations of the Code of Hammurabi, for example the translation by Robert Francis Harper, include the 13th article.


4.2. Lucky and unlucky Lucky 13

In Italy, 13 is considered a lucky number. The expression fare tredici "to do 13" means hit the jackpot. 17 is considered an unlucky number instead.


4.3. Lucky and unlucky Other

Colgate University also considers 13 a lucky number. They were founded in 1819 by 13 men with 13 dollars, 13 prayers and 13 articles. To this day, members of the Colgate community consider the number 13 a good omen. In fact, the campus address is 13 Oak Drive in Hamilton, New York, and the male a cappella group is called the Colgate 13.

In the Mayan Tzolkin calendar, trecenas mark cycles of 13-day periods. The pyramids are also set up in 9 steps divided into 7 days and 6 nights, 13 days total.

In the standard 52-card deck of playing cards there are four suits, each of 13 ranks.

In a tarot card deck, XIII is the card of Death, usually picturing the Pale horse with its rider.

A bakers dozen, devils dozen, long dozen, or long measure is 13, one more than a standard dozen.


5. Age 13

  • Thirteen is the minimum age of consent in Argentina, Burkina Faso, Japan, Niger, and two Mexican states.
  • In Judaism, thirteen signifies the age at which a boy matures and becomes a Bar Mitzvah, i.e., a full member of the Jewish faith is qualified to be counted as a member of Minyan.
  • Many states in the U.S. allow girls as young as 13 to be married with written or verbal consent from their parent.
  • On many social media platforms, thirteen is the standard minimum age to be allowed to create an account.
  • This is the age whereby a preteen becomes an adolescent in Germanic languages, due to the suffix form beginning at this point 11 & 12 are nonstandard.

6. History

  • The Great Seal of the United States bears many images of the number thirteen, representing the Thirteen Colonies from which the United States was created. On the Seals observe, the overhead glory bears thirteen stars. The chest shield in front of the spread eagle bears thirteen stripes seven white and six red. In the eagles right talon, it holds the Olive Branch of Peace, bearing thirteen olives and thirteen olive leaves. In the eagles left talon, it holds the Weapons of War, consisting of thirteen arrows. In the eagles mouth, it holds a scroll bearing the national motto "E Pluribus Unum". On the Seals reverse, the unfinished pyramid consists of thirteen levels.
  • The first flag of the United States bore thirteen stripes, alternating red and white, and thirteen white stars in the blue union. The thirteen stripes represented the Thirteen Colonies from which the United States was created, and the thirteen stars represented the number of states in the new nation. When two new states were added to the Union in 1795, the flag bore fifteen stars and fifteen stripes. With the addition of five new states in 1818, the number of stripes was re-set and permanently fixed at thirteen.
  • The United States of America was created from thirteen British colonies and as such, the number thirteen is a commonly recurring motif in American heraldry. For example, there are thirteen stars on the Great Seal of the United States and there are thirteen stripes on the American flag.
  • Apollo 13 was a NASA Moon mission famous for being a "successful failure" in 1970.


7. In sports

  • The number 13 was not used in Formula One from 1977 to 2013.
  • In rugby league
  • The number 13 was not used in the Indianapolis 500 from 1915 to 2002. It was not permitted for use between 1926 and 2002. In 2009, E.J. Viso, driving for HVM Racing in the 2009 IndyCar Series season, drove a green number 13 car full-time, despite terrible superstitions about it in motorsports.
  • The jersey number 13 is worn by the starting loose forward or lock forward in most competitions. An exception is in the Super League, which uses static squad numbering.
  • Each side has 13 players on the field at any given time.
  • Effective with the 2020 season, Major League Baseball teams are allowed no more than 13 pitchers on their active rosters at any time during the season. The main exception is from September 1 to the end of the regular season, when this number increases to 14.
  • In triathlon, the number 13 is not used. As such, the numbering goes 11, 12, 14, 15 under the current numbering system.
  • In Petanque, standard games are won when a team reaches the score of 13 points. A 13-0 score is called Fanny.
  • In rugby union, the jersey number 13 is worn by the outside centre.
  • In NCAA Division I mens college basketball, teams are allowed to provide scholarships to no more than 13 players at any given time.


8. In TV, films and literature

  • 13TH, a 2016 documentary.
  • Thirteen TV series, a 2016 British five-part police drama.
  • 13 Ghosts is a 1960 horror film.
  • 13 film, an English-language remake of the 2005 French film 13 Tzameti.
  • Thirteen Ghosts a 2001 remake.
  • Thirteen film, a 2003 American film.
  • 13 musical, a 2007 musical.
  • Number 13 film, an uncompleted Hitchcock 1922 film.
  • 13 Tzameti, a 2005 French film "Tzameti" means "13" in Georgian.
  • The Thirteenth Floor is a 1999 sci-fi film.
  • The 13th Warrior is a 1999 historical fiction action film starring Antonio Banderas.
  • Thirteen Reasons Why is a novel containing 13 tapes received by a student learning of his classmates suicide and death.
  • The Thirteen is a 1936 Soviet war film by Mikhail Romm.
  • The 13 Ghosts of Scooby-Doo: Seventh incarnation of the Hanna-Barbera Scooby-Doo cartoon franchise, first run 1985-1986.
  • Thirteen is the nickname of Dr. Remy Hadley on the American medical drama House played by Olivia Wilde.
  • Warehouse 13 is a television show about the 13th warehouse in the line of warehouses that store supernatural artifacts.
  • Apollo 13 is a 1995 American film.
  • 13 Assassins is a 2010 film by Japanese director Takashi Miike.
  • 13B/Yaavarum Nalam is a 2009 Hindi/Tamil Horror movie starring R Madhavan.
  • Friday the 13th: The Series is a syndicated American-Canadian horror television series, that originally ran from 1987 to 1990.
  • Friday the 13th is a horror film series involving a mass murderer named Jason Voorhees.
  • District 13 is a 2004 French film with David Belle.