131
domain: N
Properties
Digital Properties
- Digit Count
- 3
- Digit Sum
- 5
- Digital Root
- 5
- Palindromic Number
- yes
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 132
- Proper Divisor Sum (Aliquot Sum)
- 1
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Highly Composite
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 130
- Möbius Function
- -1
- Radical
- 131
- Omega Function (Ω)
- 1
- Little Omega Function (ω)
- 1
Special
- Factorial
- no
- Catalan Number
- no
- Bell Number
- no
- Motzkin Number
- no
- Primorial
- no
Figurate Numbers
- Fibonacci Number
- no
- Triangular Number
- no
- Perfect Square
- no
- Perfect Cube
- no
- Pentagonal Number
- no
- Hexagonal Number
- no
- Lucas Number
- no
- Tetrahedral Number
- no
- Pell Number
- no
- Tribonacci Number
- no
- Pronic Number
- no
Recreational
- Happy Number
- no
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 28
- Smith Number
- no
Primality
- Prime
- yes
- Composite Number
- no
- Semiprime
- no
- Squarefree Number
- yes
- Prime Power
- yes
- Prime Factorization
- no
- Twin Prime
- no
- Mersenne Prime
- no
- Sophie Germain Prime
- yes
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Prime Index
- 32
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Names
- German
- einshunderteinunddreißig· ordinal: einshunderteinunddreißigste
- English
- one hundred thirty-one· ordinal: one hundred thirty-first
- Spanish
- ciento treinta y uno· ordinal: 131º
- French
- cent trente et un· ordinal: cent trente et unième
- Italian
- centotrentuno· ordinal: 131º
- Latin
- centum triginta unus· ordinal: 131.
- Portuguese
- cento e trinta e um· ordinal: 131º
Appears in sequences
- Coefficients of the 3rd-order mock theta function f(q).at n=33A000025
- Let k = p_1^e_1 p_2^e_2 p_3^e_3 ... be the prime factorization of n. Sequence gives k such that the sum of the numbers of 1's in the binary expansions of e_1, e_2, e_3, ... is odd.at n=62A000028
- Positive zeros of Bessel function of order 0 rounded to nearest integer.at n=41A000134
- Coefficient of q^(2n-1) in the series expansion of Ramanujan's mock theta function f(q).at n=16A000199
- Primes p == 3, 9, 11 (mod 20) such that 2p+1 is also prime.at n=6A000355
- Numbers that are the sum of 3 but no fewer nonzero squares.at n=54A000419
- Primes and squares of primes.at n=36A000430
- n written in base where place values are positive cubes.at n=52A000433
- Number of nonnegative solutions of x^2 + y^2 = z in first n shells.at n=61A000592
- Number of paraffins C_n H_{2n-1} XYZ with n carbon atoms.at n=5A000640
- n-th superior highly composite number A002201(n) is product of first n terms of this sequence.at n=50A000705
- Numbers beginning with a vowel in English.at n=45A000852
- Numbers ending with a vowel in American English.at n=58A000861
- Numbers beginning with letter 'o' in English.at n=32A000865
- Number of twin prime pairs < square of n-th prime.at n=20A000885
- Irregular primes: primes p such that at least one of the numerators of the Bernoulli numbers B_2, B_4, ..., B_{p-3} (A000367) is divisible by p.at n=5A000928
- Dimension of the n-th graded piece of the mod-2 Steenrod algebra A_2.at n=48A000929
- Powers of primes. Alternatively, 1 and the prime powers (p^k, p prime, k >= 1).at n=45A000961
- a(n) = a(n-1) + a(n-2) with a(0)=2, a(1)=5. Sometimes called the Evangelist Sequence.at n=8A001060
- Primes with primitive root 2.at n=14A001122