12808
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 19
- Digital Root
- 1
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 24030
- Proper Divisor Sum (Aliquot Sum)
- 11222
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 6400
- Möbius Function
- 0
- Radical
- 3202
- Omega Function (Ω)
- 4
- 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
- yes
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 63
- 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
- yes
- Odd
- no
Appears in sequences
- Number of hooked Skolem sequences of order n.at n=9A004076
- Base-7 palindromes that start with 5.at n=32A043019
- Indices of primes in sequence defined by A(0) = 57, A(n) = 10*A(n-1) - 53 for n > 0.at n=2A101571
- Integers n such that 9*10^n + 11 is a prime number.at n=18A111023
- Expansion of (chi(-x) * chi(-x^19))^(-2) in powers of x where chi() is a Ramanujan theta function.at n=29A134004
- Binomial transform of [1, 2, 3, 4, 0, 0, 0, ...].at n=27A139488
- For positive n with prime decomposition n = Product_{j=1..m} (p_j^k_j) define A_n = Sum_{j=1..m} (p_j*k_j) and B_n = Sum_{j=1..m} (p_j^k_j). This sequence gives those n for which A_n and B_n are both prime and B_n = A_n + 2 (i.e., form a twin prime pair).at n=28A185718
- a(n) = 204*2^n - 248.at n=5A278122
- Irregular table read by rows: T(n,k) is the number of k-gons, k>=2, among all distinct circles that can be constructed from a 2 x n square grid of points using only a compass.at n=51A359862
- Third Lie-Betti number of a path graph on n vertices.at n=39A361230
- Irregular triangle read by rows: T(N,k) (0 <= k <= 4*N^2) are coefficients of cluster density function for site percolation on a 2*N X 2*N 2D union jack lattice with periodic boundary conditions.at n=14A365943
- Index of n-th prime in A386482, or -1 if that prime is missing.at n=49A386483
- a(n) is the index where A387090(n) appears in A386482.at n=21A386484