631
domain: N
Properties
Digital Properties
- Digit Count
- 3
- Digit Sum
- 10
- Digital Root
- 1
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 632
- 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
- 630
- Möbius Function
- -1
- Radical
- 631
- 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
- 38
- 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
- no
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Prime Index
- 115
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Names
- German
- sechshunderteinunddreißig· ordinal: sechshunderteinunddreißigste
- English
- six hundred thirty-one· ordinal: six hundred thirty-first
- Spanish
- seiscientos treinta y uno· ordinal: 631º
- French
- six cent trente et un· ordinal: six cent trente et unième
- Italian
- seicentotrentuno· ordinal: 631º
- Latin
- sescenti triginta unus· ordinal: 631.
- Portuguese
- seiscentos e trinta e um· ordinal: 631º
Appears in sequences
- Central polygonal numbers (the Lazy Caterer's sequence): n(n+1)/2 + 1; or, maximal number of pieces formed when slicing a pancake with n cuts.at n=35A000124
- Number of tertiary alcohols (alkanols or alkyl alcohols C_n H_{2n+1} OH) with n carbon atoms.at n=12A000600
- Numbers k such that (1,k) is "good".at n=14A000696
- Primes p of the form 3k+1 such that sum_{x=1..p} cos(2*Pi*x^3/p) < -sqrt(p).at n=11A000923
- 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=39A000928
- Primes with 3 as smallest primitive root.at n=27A001123
- A sequence of sorted odd primes 3 = p_1 < p_2 < ... < p_m such that p_i-2 divides the product p_1*p_2*...*p_(i-1) of the earlier primes and each prime factor of p_i-1 is a prime factor of twice the product.at n=11A001259
- Number of ways of making change for n cents using coins of 1, 2, 5, 10, 25, 50 cents.at n=58A001302
- Cyclic numbers: 10 is a quadratic residue modulo p and class of mantissa is 2.at n=37A001914
- Prime determinants of forms with class number 2.at n=53A002052
- a(n) = least primitive factor of 2^(2n+1) - 1.at n=22A002184
- Smallest prime p such that first n primes (p_1=2, ..., p_n) are 7th power residues mod p.at n=0A002227
- Cuban primes: primes which are the difference of two consecutive cubes.at n=9A002407
- Primes p with a Fibonacci primitive root g, i.e., such that g^2 = g + 1 (mod p).at n=35A003147
- Hex (or centered hexagonal) numbers: 3*n*(n+1)+1 (crystal ball sequence for hexagonal lattice).at n=14A003215
- Nonsquare values of m in the discriminant D = 4*m leading to a new maximum of the L-function of the Dirichlet series L(1) = Sum_{k>0} Kronecker(D,k)/k.at n=17A003421
- Divisors of 2^45 - 1.at n=7A003550
- Triangular numbers written backwards.at n=16A004158
- Divisible only by primes congruent to 1 mod 5.at n=30A004615
- Numbers divisible only by primes congruent to 1 mod 7.at n=18A004619