8131
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 13
- Digital Root
- 4
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 8352
- Proper Divisor Sum (Aliquot Sum)
- 221
- 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
- 7912
- Möbius Function
- 1
- Radical
- 8131
- Omega Function (Ω)
- 2
- Little Omega Function (ω)
- 2
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
- 127
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- yes
- Squarefree Number
- yes
- Prime Power
- no
- Prime Factorization
- no
- Twin Prime
- no
- Mersenne Prime
- no
- Sophie Germain Prime
- no
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Numbers whose base-4 representation contains exactly two 0's and four 3's.at n=22A045075
- a(1) = 6; a(n) is smallest number >= a(n-1) such that the juxtaposition a(1)a(2)...a(n) is a prime.at n=44A046256
- Numbers k such that k^2 contains only digits {1,3,6}.at n=10A053892
- The sequence S(n,-3,1,1), where S(n,k,t,q) is defined by Sum_{j=0..n} binomial(n+q,j)^t * B(j,k) and B(j,k) is the j-th k-poly-Bernoulli number.at n=4A068518
- Numbers k such that k, k+2, k+4, k+6, k+8 are semiprimes.at n=24A092127
- Numbers k such that k, k+2, k+4, k+6, k+8, k+10 are semiprimes.at n=5A092128
- Numbers k such that k, k+2, k+4, k+6, k+8, k+10, k+12 are semiprimes.at n=2A092129
- a(n) = a(n-1) + a(n-2) + a(n-4) with a(0) = 2, a(1) = 3, a(2) = 6, a(3) = 9.at n=15A095982
- Number of partitions of n with more odd parts than even parts.at n=33A108950
- Numbers k such that k and k^2 use only the digits 0, 1, 3, 6 and 8.at n=9A136849
- Numbers k such that k and k^2 use only the digits 1, 2, 3, 6 and 8.at n=5A136980
- Numbers k such that k and k^2 use only the digits 1, 3, 4, 6 and 8.at n=13A137026
- Numbers k such that k and k^2 use only the digits 1, 3, 5, 6 and 8.at n=8A137034
- Numbers k such that k and k^2 use only the digits 1, 3, 6, 7 and 8.at n=5A137038
- Numbers k such that k and k^2 use only the digits 1, 3, 6 and 8.at n=2A137040
- Numbers k such that k and k^2 use only the digits 1, 3, 6, 8 and 9.at n=16A137041
- Number of n X n binary arrays symmetric under 180 degree rotation with all ones connected only in a 10001-11111-00100 pattern in any orientation.at n=11A147391
- Numbers n with property that the sum of the digits of n is substring of n and of n^2.at n=44A162015
- G.f. satisfies: A(x) = exp( Sum_{n>=1} sigma(n)*A(x^n)*x^n/n ).at n=10A179467
- Table read by antidiagonals of numbers of form (2^n -1)*2^(m+2) + 3 where n>=1, m>=1.at n=51A224380