13520
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 11
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 30
- Divisor Sum
- 34038
- Proper Divisor Sum (Aliquot Sum)
- 20518
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 4992
- Möbius Function
- 0
- Radical
- 130
- Omega Function (Ω)
- 7
- Little Omega Function (ω)
- 3
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
- 45
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- Squarefree Number
- no
- 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
- yes
- Odd
- no
Appears in sequences
- Product of sums of divisors and non-divisors.at n=26A066859
- Numbers n such that A001414(n) = sum of squared digits of n.at n=25A094908
- Norm of the sum of divisors function sigma(n) generalized for Gaussian integers.at n=44A103230
- a(n) = binomial(n,4) - binomial(floor(n/2),4) - binomial(ceiling(n/2),4).at n=26A111385
- Expansion of g.f.: (1+x+x^2)/(1-4*x-4*x^2).at n=6A123871
- Number of ways to place 2 nonattacking knights on an n X n toroidal board.at n=12A172529
- Number of ways to place 2 nonattacking kings on an n X n toroidal board.at n=12A179403
- a(n) = 20*n^2.at n=26A195322
- Integer quotients of k^2 by the sum of the prime distinct divisors of k^2+1, where k = A196219(n).at n=4A196220
- Number of ordered triples (w,x,y) with all terms in {1,...,n} and w^2>2x^2+2y^2.at n=24A211633
- Composite numbers n such that Sum_{d_<n | n} phi(d_<n) / (d_<n) is an integer, where d_<n = divisors of n that are less than n, phi(x) = A000010(x).at n=29A211778
- Numbers n such that the sum of prime factors of n (counted with repetition) equals three times the largest prime divisor.at n=38A212861
- Triangular array read by rows. T(n,k) is the number of partitions of n (using 1 type of part 1, 2 types of part 2, ..., i types of part i, ...) that have exactly k distinct parts.at n=69A216221
- Triangle numbers: m = a*b*c such that the integers a,b,c are the sides of a triangle with integer area.at n=40A218243
- Number of arrays of length n that are sums of 4 consecutive elements of length n+3 permutations of 0..n+2, and no two consecutive rises or falls in the latter permutation.at n=5A229714
- T(n,k) = number of arrays of length n that are sums of k consecutive elements of length n+k-1 permutations of 0..n+k-2, and no two consecutive rises or falls in the latter permutation.at n=41A229717
- Number of arrays of length 6 that are sums of n consecutive elements of length 6+n-1 permutations of 0..6+n-2, and no two consecutive rises or falls in the latter permutation.at n=3A229722
- Number of n X 6 0..2 arrays with no element equal to one plus the sum of elements to its left or one plus the sum of elements above it or one plus the sum of the elements diagonally to its northwest, modulo 3.at n=19A239359
- n! mod n^3.at n=25A242427
- Numbers n = concat(x,y) such that the product x*y | n. No leading zeros in y allowed.at n=29A255726