# 131 (number)

Short description: Natural number
 ← 130 131 132 →
Cardinalone hundred thirty-one
Ordinal131st
(one hundred thirty-first)
Factorizationprime
Prime32nd
Divisors1, 131
Greek numeralΡΛΑ´
Roman numeralCXXXI
Binary100000112
Ternary112123
Quaternary20034
Quinary10115
Senary3356
Octal2038
DuodecimalAB12
Vigesimal6B20
Base 363N36

131 (one hundred [and] thirty-one) is the natural number following 130 and preceding 132.

## In mathematics

131 is a Sophie Germain prime,[1] an irregular prime,[2] the second 3-digit palindromic prime, and also a permutable prime with 113 and 311. It can be expressed as the sum of three consecutive primes, 131 = 41 + 43 + 47. 131 is an Eisenstein prime with no imaginary part and real part of the form $\displaystyle{ 3n - 1 }$. Because the next odd number, 133, is a semiprime, 131 is a Chen prime. 131 is an Ulam number.[3]

131 is a full reptend prime in base 10 (and also in base 2). The decimal expansion of 1/131 repeats the digits 007633587786259541984732824427480916030534351145038167938931 297709923664122137404580152671755725190839694656488549618320 6106870229 indefinitely.

## In transportation

• London Buses route 131 is a Transport for London contracted bus route in London
• The Fiat 131 Mirafiori small/medium family car produced from 1974 to 1984
• STS-131 is a NASA Contingency Logistic Flight (CLF) of the Space Shuttle Atlantis which launched in April 2010

## In other fields

131 is also:

• The year AD 131 or 131 BC
• 131 AH is a year in the Islamic calendar that corresponds to 748 – 749 CE.
• 131 Vala is an inner main belt asteroid
• Iodine-131, or radioiodine, is a radioisotope of iodine for medical and pharmaceutical use
• ACP-131 is the controlling publication for listing of Q codes and Z codes, as published by NATO Allied countries
• Sonnet 131 by William Shakespeare
• 131 is the medical emergency telephone number in Chile
• United States Citizenship and Immigration Services Form I-131 to apply for a travel document, reentry permit, refugee travel document or advance parole
• 131 is the ID3v1 tag equivalent to Indie music