17661
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 21
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 12
- Divisor Sum
- 27872
- Proper Divisor Sum (Aliquot Sum)
- 10211
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 9744
- Möbius Function
- 0
- Radical
- 609
- Omega Function (Ω)
- 4
- 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
- yes
- Narcissistic Number
- no
- Collatz Steps
- 172
- 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
- no
- Odd
- yes
Appears in sequences
- a(n) is the number of forests with n (unlabeled) nodes in which each component tree is planted, that is, is a rooted tree in which the root has degree 1.at n=13A005198
- Number of paraffins.at n=40A005997
- Expansion of 1/((1-4x)(1-5x)(1-8x)).at n=4A018250
- a(n) = n*(2*n^2 - 2*n + 1).at n=21A059722
- a(n) = 21*n^2.at n=29A064762
- Numbers n for which there are exactly seven k such that n = k + reverse(k).at n=36A072431
- Output of the linear congruential pseudo-random number generator used in function rand() as described in Kernighan and Ritchie, when seeded with 0.at n=19A096554
- a(n) = ceiling(n/2)*ceiling(n^2/2).at n=41A131474
- G.f.: A(q) = exp( Sum_{n>=1} A162552(n) * 3*A038500(n) * q^n/n ).at n=27A161808
- Numbers k such that phi(k)/k = 16/29.at n=6A172344
- G.f.: Sum_{n>=0} x^n * Product_{k=1..n} (1+x^k)/(1-x^k).at n=25A207641
- Number of (w,x,y,z) with all terms in {1,...,n} and w > harmonic mean of {x,y,z}.at n=13A212105
- Apparently solves the identity: find sequence B that represents the numbers of ordered compositions of n using the terms of A, and vice versa.at n=17A224342
- Expansion of g.f. 1/ (1-x^1*(1-x^(m+1))/ (1-x^2*(1-x^(m+2))/ (1- ... ))) for m=7.at n=20A228644
- Number of n-digit lunar primes obtained by promoting the binary templates.at n=4A235641
- Number of partitions p of n such that the multiplicity of the median of p is a part of p.at n=42A240492
- Numbers n such that 2*n + prime(n) is a square.at n=37A256246
- Number of active (ON, black) cells at stage 2^n-1 of the two-dimensional cellular automaton defined by "Rule 470", based on the 5-celled von Neumann neighborhood.at n=7A272420
- p-INVERT of (0,1,0,1,0,1,...), where p(S) = (1 - S)(1 - 3 S).at n=7A291236
- Numbers k such that k and k+1 are both hoax numbers (A019506).at n=32A329935