12918
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
- 25848
- Proper Divisor Sum (Aliquot Sum)
- 12930
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- yes
Derived Values
- Euler's Totient
- 4304
- Möbius Function
- -1
- Radical
- 12918
- 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
- 76
- 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
- Harmonic Molien series for Conway group Con.0.at n=41A008924
- a(1) = 932; for n > 1, a(n) = a(n-1) + 1 + sum of distinct prime factors of a(n-1) that are < a(n-1).at n=35A105213
- Triangle read by rows: T(n,k) = is the number of directed column-convex polyominoes of area n having along the lower contour exactly k reentrant corners, i.e., a vertical step that is followed by a horizontal step (n >= 1, k >= 0).at n=53A121466
- Admirable numbers in the middle of twin primes.at n=33A135502
- Triangle T(n, k) = Fibonacci(2*k)*T(n-1, k) + Fibonacci(2*(n-k+1))*T(n-1, k-1), with T(n, 1) = T(n, n) = 1, read by rows.at n=37A141688
- Triangle T(n, k) = Fibonacci(2*k)*T(n-1, k) + Fibonacci(2*(n-k+1))*T(n-1, k-1), with T(n, 1) = T(n, n) = 1, read by rows.at n=43A141688
- The number of degree sequences with degree sum 2n representable by a non-separable graph (with multiple edges allowed).at n=22A147877
- Numbers that are divisible by exactly 3 primes (counted with multiplicity) and sandwiched between primes.at n=32A171179
- Number of ternary strings of length n which contain 01.at n=9A186314
- Diagonal sums of the Riordan matrix (1/(1-3*x^2),x/(1-x)) (A191582).at n=17A191584
- Numbers n such that n^3+prime(n) and n^3-prime(n) are prime.at n=30A257788
- Number of n X 3 binary arrays with rows and columns lexicographically nondecreasing and column sums nonincreasing.at n=13A266465
- Numbers of the form prime(i-1)+prime(i+1) that are the average of a twin prime pair.at n=44A342993
- Numbers that are the sum of nine fourth powers in nine or more ways.at n=22A345593
- Numbers that are the sum of nine fourth powers in exactly nine ways.at n=20A345851
- Number of compositions (ordered partitions) of n into at most 5 prime powers (including 1).at n=36A347775
- Midpoints k of a pair of twin primes such that sigma(k) is also the midpoint of a pair of twin primes.at n=24A349981
- Number of integer compositions of n whose leaders of weakly decreasing runs are themselves weakly decreasing.at n=18A374747