113 (number)

113 (one hundred [and] thirteen) is the natural number following 112 and preceding 114.

Mathematics[]

• 113 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,^[1] a Chen prime^[2] and a Proth prime as it is a prime number of the form 7 × 2⁴ + 1. 113 is also an Eisenstein prime with no imaginary part and real part of the form ${\displaystyle 3n-1}$. In base 10, this prime is a primeval number,^[3] and a permutable prime with 131 and 311.
• 113 is a highly cototient number^[4] and a centered square number.^[5]
• 355/113 approximates π to six decimal places, with an error of less than 1/113³. This means that 113/355 approximates the reciprocal of π.
• 113 is the smallest positive integer that cannot be represented in the Four fours problem using standard rules. It can be solved using the gamma function.^{[clarification needed][dubious – discuss]}

Religion[]

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

Science[]

• 113, the atomic number of the element nihonium
• Cadmium-113m, a radioisotope and nuclear isomer with a halflife of 14.1 years

Telephony[]

113 is:

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

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"

See also[]

• List of highways numbered 113
• M113 (disambiguation)
• A113
• 11/3 (disambiguation)

References[]

• Wells, D. The Penguin Dictionary of Curious and Interesting Numbers London: Penguin Group. (1987): 134