15623
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 17
- Digital Root
- 8
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 16560
- Proper Divisor Sum (Aliquot Sum)
- 937
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 14688
- Möbius Function
- 1
- Radical
- 15623
- 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
- yes
- Narcissistic Number
- no
- Collatz Steps
- 252
- 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
- a(n) = n*(27*n + 1)/2.at n=34A022285
- Ordered sequence of distinct terms of the form floor(x^i * floor(x^j)), i,j >= 0, where x = sqrt(5).at n=39A022770
- Consider all integer triples (i,j,k), j,k>0, with binomial(i+2, 3) = binomial(j+2, 3) + k^3, ordered by increasing i; sequence gives j values.at n=42A054222
- "Orderly" Friedman numbers (or "good" or "nice" Friedman numbers): Friedman numbers (A036057) where the construction digits are used in the proper order.at n=27A080035
- a(1) = 1, a(2) = 1, a(n+1) = 2n*a(n) - a(n-1). Symmetrically a(n) = (a(n-1) + a(n+1))/((n-1) + (n+1)).at n=6A093986
- Number of compositions of n in which the greatest part is even.at n=15A103422
- Semiprime nearest to 5^n. In case of a tie, choose the smaller.at n=6A117429
- Limiting values of A136406: a(n) = A136406(m,m-n) for any m >= 2n.at n=27A137504
- G.f.: exp( Sum_{n>=1} [Sum_{k=0..n} C(n,k)^4 * x^k] * x^n/n ), an integer series in x.at n=8A166898
- Partial sums of A048995.at n=47A174514
- Numbers which contain only the digit 4 in their base-5 representation, with at most one exception. If the exception is the most-significant digit, it must be the digit 1, 2, or 3, otherwise the exception must be the digit 3.at n=37A188531
- Friedman numbers n such that n+1 is also a Friedman number.at n=37A195420
- Number of (w,x,y) with all terms in {0,...,n} and the numbers w,x,y,|w-x|,|x-y| not distinct.at n=40A213491
- Numbers, a(n) where binomial(a(n), 5n-1) == 0 (mod 5) and binomial(a(n), k) != 0 (mod 5) for k != 5n - 1.at n=19A224251
- Indices of primes in A100683.at n=17A232543
- a(n) = n*(3*n^2 + 3*n + 1).at n=17A249354
- Number of maximum irredundant sets in the n-Hanoi graph.at n=2A308384
- Triangle read by rows: T(n,k) = number of tilings of a n X k rectangle using 2 X 2 and 1 X 1 tiles and dominoes, n >= 0, k = 0..n.at n=14A352589
- Number of tilings of a 4 X n rectangle using 2 X 2 and 1 X 1 tiles and dominoes.at n=4A352590
- Number of tilings of an n X n square using dominoes, monominoes and 2 X 2 tiles.at n=4A353777