15521
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 14
- Digital Root
- 5
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 18144
- Proper Divisor Sum (Aliquot Sum)
- 2623
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 13120
- Möbius Function
- -1
- Radical
- 15521
- Omega Function (Ω)
- 3
- 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
- 133
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- 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
- Pseudoprimes to base 84.at n=38A020212
- Number of different words that can be formed from an n X n grid of letters, reading horizontally, vertically or diagonally.at n=16A034720
- The sequence e when b=[ 1,0,1,1,1,... ].at n=40A042953
- Triangle read by rows: T(n,k) = number of noncommutative symmetric polynomials of degree n that have exactly k different variables appearing in each monomial and which generate the algebra of all noncommutative symmetric polynomials (n >= 1, 1 <= k <= n).at n=48A055105
- Triangle T(n,k) giving number of symmetric polynomials of degree n in k noncommuting variables, n >=2, 2 <= k <= n.at n=38A055106
- Triangle T(k,n) giving number of symmetric polynomials of degree n in k noncommuting variables, n >=2, 2 <= k <= n.at n=42A055107
- a(n) = Sum_{k=0..n} C(2k+2,k).at n=7A057552
- Number of identity (asymmetric) bracelets (or necklaces) with n red and blue beads such that the beads switch colors when bracelet is turned over.at n=7A066316
- a(n) = Sum_{k=0..n} (-1)^(n-k)*binomial(k,floor(k/2)).at n=17A086905
- a(n) = Sum_{k <= n/2 } binomial(n-2k, 3k+1).at n=20A137357
- a(n) = 1 + (144 + (50 + (35 + (10 + n)*n)*n)*n)*n/120.at n=16A145127
- a(n) = 36*n^2 - 17*n + 2.at n=20A157265
- Number of (n+1)xn binary matrices with rows and columns each in strictly increasing order as binary numbers and no 1 neighboring another 1.at n=7A180998
- Number of base pyramids in all length n left factors of Dyck paths.at n=17A191790
- a(n) = n*(7*n^2-12*n+7)/2.at n=17A226451
- a(n) = Sum_{i=1..n} ( Product_{k|i} d(k) ), where d(n) = A000005(n).at n=32A237349
- Number of (n+1) X (1+1) arrays of permutations of 0..n*2+1 with each element having directed index change -2,0 -1,0 0,-1 or 1,1.at n=29A264622
- Number of active (ON, black) cells at stage 2^n-1 of the two-dimensional cellular automaton defined by "Rule 846", based on the 5-celled von Neumann neighborhood.at n=7A273688
- a(n) is the smallest positive integer which can be represented as the sum of distinct nonzero dodecahedral numbers in exactly n ways, or -1 if no such integer exists.at n=4A360216
- Partial sums of A224613.at n=44A365446