12666
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
- 8
- Divisor Sum
- 25344
- Proper Divisor Sum (Aliquot Sum)
- 12678
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- yes
Derived Values
- Euler's Totient
- 4220
- Möbius Function
- -1
- Radical
- 12666
- 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
- 169
- 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
- yes
- Odd
- no
Appears in sequences
- Stopping times.at n=11A007186
- Poincaré series [or Poincare series] for depths of roots in a certain root system.at n=24A019527
- Positive numbers k such that k and 5*k are anagrams in base 8 (written in base 8).at n=9A023076
- Beastly (or hateful) numbers: numbers containing the string 666 in their decimal expansion.at n=21A051003
- a(n) = Sum_{k=1..n} antisigma(k), where antisigma(i) = sum of the nondivisors of i that are between 1 and i.at n=42A076664
- Numbers n with digits in nondecreasing order such that sum of the reciprocal of digits is an integer.at n=26A091784
- Triangle of coefficients of polynomials u(n,x) jointly generated with A209140; see the Formula section.at n=52A209139
- Numbers k such that (5*10^k - 143)/3 is prime.at n=22A271821
- E.g.f. equals the limit of the average of all permutations of the compositions of the functions x*exp(x^k), for k=1..n, as n increases.at n=5A278332
- Least integer N > 2 such that the number of primes (<=N) <= the number of base-n-zero containing numbers (<=N).at n=21A306521
- Positive integers that have exactly nine representations of the form 1 + p1 * (1 + p2* ... * (1 + p_j)...), where [p1, ..., p_j] is a (possibly empty) list of distinct primes.at n=16A317399
- Numbers m such that 18*m + 1, 36*m + 1, 108*m + 1, and 162*m + 1 are all primes.at n=38A372188
- Array read by antidiagonals: Place k points in general position on each side of a regular n-gon and join every pair of the k*n boundary points by a chord; T(n,k) (n >= 3, k >= 0) gives the number of vertices in the resulting planar graph.at n=45A392261