16611
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 15
- Digital Root
- 6
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 12
- Divisor Sum
- 25992
- Proper Divisor Sum (Aliquot Sum)
- 9381
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 9408
- Möbius Function
- 0
- Radical
- 2373
- 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
- no
- Narcissistic Number
- no
- Collatz Steps
- 128
- 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
- Number of inequivalent ways to color vertices of a regular tetrahedron using <= n colors.at n=21A006008
- a(n) = floor( binomial(n,7)/7 ).at n=21A011853
- [ n(n-1)(n-2)(n-3)/7 ].at n=20A011917
- a(n) = 1*t(n) + 2*t(n-1) + ...+ k*t(n+1-k), where k=floor((n+1)/2) and t is A001950 (upper Wythoff sequence).at n=40A023867
- a(n) = s(1)s(n) + s(2)s(n-1) + ... + s(k)s(n+1-k), where k = [ (n+1)/2 ], s = A000201 (lower Wythoff sequence).at n=41A024685
- a(n) = s(1)s(n) + s(2)s(n-1) + ... + s(k)s(n-k+1), where k = [ n/2 ], s = A000201 (lower Wythoff sequence).at n=40A025118
- Second differences of Motzkin numbers (A001006).at n=10A026107
- Number of orbits of length n under the map whose periodic points are counted by A005809.at n=6A060170
- Number of board-pair-pile hexagonal polyominoes with n cells.at n=7A068091
- Least m such that reverse(sigma(m)) = sigma(m+n).at n=18A071813
- Number of partitions of n into decimal repdigit numbers.at n=40A088669
- Number of partitions of n into decimal palindromes.at n=40A091580
- Numbers k such that k^4 contains a pandigital substring.at n=32A115934
- Sum of squares of three consecutive primes.at n=19A133529
- a(n) = 1/7*( binomial(n,7) - floor(n/7) ).at n=13A215053
- Semiperimeters s of primitive Pythagorean triples (a, b, c) where a, b, c and s are not squarefree.at n=34A237620
- Number of compositions of n with c(1) = 1, c(i+1) - c(i) <= 1, and c(i+1) - c(i) != 0.at n=37A238870
- Numbers using only digits 1 and 6.at n=42A284293
- Sum of the squarefree parts of the partitions of n into 9 parts.at n=31A309485
- A triple of positive integers (n,p,k) is admissible if there exist at least two different multisets of k positive integers, {x_1,x_2,...,x_k} and {y_1,y_2,...,y_k}, such that x_1+x_2+...+x_k = y_1+y_2+...+y_k = n and x_1x_2...x_k = y_1y_2...y_k = p. For each n, let A(n) = {p:(n,p,k) is admissible for some k}, and let a(n) = |A(n)|.at n=61A316946