15657
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 24
- Digital Root
- 6
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 22176
- Proper Divisor Sum (Aliquot Sum)
- 6519
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 9792
- Möbius Function
- -1
- Radical
- 15657
- 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
- 84
- 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
- a(n) is the solution to the postage stamp problem with 4 denominations and n stamps.at n=31A001209
- 4-dimensional analog of centered polygonal numbers.at n=18A006325
- a(n) = binomial(n+2, 2) + binomial(n+4, 5).at n=16A027658
- Numbers whose base-5 representation contains exactly three 0's and three 1's.at n=10A045172
- a(1) = 9, then the smallest number such that the forward as well as the reverse n-th partial concatenation is a prime for n>1. (Reverse concatenation is taken term-wise and not digit-wise).at n=26A083995
- Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, 0, 0), (-1, 0, 1), (0, 0, -1), (1, -1, 1), (1, 1, 0)}.at n=8A149465
- Number of (w,x,y) with all terms in {0,...,n} and w<x+y and x<y.at n=33A212980
- Primitive numbers in A229306.at n=35A229310
- a(n) = n*(n + 1)*(19*n - 16)/6.at n=17A237618
- Numbers of the form 5^x + y^5 with x, y >= 0.at n=43A250546
- a(n) = A289670(n)/2^f(n), where f(n) = 2*floor((n-1)/3) + ((n+2) mod 3).at n=47A289676
- a(n) = A289676(3*n).at n=15A290438
- Numbers m such that the numerator of Sum_{k=1..m, gcd(k,m) = 1} 1/k is divisible by m^3.at n=38A290815
- Numbers of the form a^5 + b^6, with integers a, b > 0.at n=25A303375
- Numbers m such that the numerator of Sum_{k=1..m, gcd(k,m) = 1} 1/k^2 is divisible by m^2.at n=50A309696
- a(n) = Sum_{k=0..floor(n/3)} binomial(4*n-2*k,n-3*k).at n=5A371755
- a(n) = (1/3) * Sum_{k=0..n-1} binomial(6*n,6*k+2).at n=3A387746