# 131 (number)

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 ← 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
Hexadecimal8316
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.

131 is also:

## References

1. ^ "Sloane's A005384 : Sophie Germain primes". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-27.
2. ^ "Sloane's A000928 : Irregular primes". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-27.
3. ^ "Ulam numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. 2016-04-18. Retrieved 2016-04-19.