# ⓘ 113 (number)

## ⓘ 113 (number)

• 113 is the natural number following 112 and preceding 114.
• 113 is a highly cototient number and a centered square number.
• It is the 30th prime number following 109 and preceding 127, so it can only be divided by one and itself. 113 is a Sophie Germain prime, a Chen prime and a Proth prime as it is a prime number of the form 7 × 2 4 + 1. 113 is also an Eisenstein prime with no imaginary part and real part of the form 3 n − 1 {\displaystyle 3n-1}. In base 10, this prime is a primeval number, and a permutable prime with 131 and 311.
• 355/113 approximates pi to six decimal places, with an error of less than 1/113 3. This means that 113/355 approximates the reciprocal of pi.
• 113 is the smallest positive integer that cannot be represented in the Four fours problem using standard rules.

## 1. Religion

• Psalms 113–118 constitute the Hallel, which is recited on the three great feasts: Passover, Weeks, and Tabernacles
• 113, the number of surah al-Falaq in the Quran

## 2. Telephony

113 is:

• The time telephone number in Argentina
• The medical emergency telephone number in Latvia and Norway
• The fire emergency telephone number in Indonesia
• The intelligence agency telephone number in Iran
• The police emergency telephone number in Italy, Luxembourg, Slovenia, and Vietnam

## 3. Other uses

• 113 band, a French hip hop group
• 113, the port number of the IDENT Internet protocol that helps identify the user of a particular TCP connection
• 113, in enduro, is regarded as an unlucky number to be given to a race entrant and is colloquially known as a "blind pew"