12765
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
- 2
Divisibility
- Divisor Count
- 16
- Divisor Sum
- 21888
- Proper Divisor Sum (Aliquot Sum)
- 9123
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 6336
- Möbius Function
- 1
- Radical
- 12765
- Omega Function (Ω)
- 4
- Little Omega Function (ω)
- 4
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
- no
- Odd
- yes
Appears in sequences
- Maximal planar degree sequences with n nodes.at n=14A007020
- McKay-Thompson series of class 9B for the Monster group.at n=28A058091
- a(n) = (4*n+3)*(4*n+7).at n=27A085027
- 4-almost primes equal to the product of two successive semiprimes.at n=35A108215
- Primitive elements of A119432.at n=26A119433
- Transform of A000027 by the T_{1,1} transformation (see link).at n=10A136302
- Padovan-like sequence; a(0)=2, a(1)=1, a(2)=1, a(n) = a(n-2) + a(n-3).at n=34A141038
- First trisection of A061037 (Balmer line series of the hydrogen atom).at n=37A142590
- a(n) = prime(n)^2-4.at n=29A166010
- Quintisection A061037(5*n-2).at n=23A174850
- Triangle read by rows: T(n,k) is the number of weighted lattice paths in L_n having k (1,0)-steps of weight 2. These are paths that start at (0,0) , end on the horizontal axis and whose steps are of the following four kinds: an (1,0)-step with weight 1; an (1,0)-step with weight 2; a (1,1)-step with weight 2; a (1,-1)-step with weight 1. The weight of a path is the sum of the weights of its steps.at n=59A182885
- Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 873", based on the 5-celled von Neumann neighborhood.at n=21A273709
- Integers that are the sum of two consecutive semiprimes, as well as the product of two consecutive semiprimes.at n=5A288955
- Number of 5Xn 0..1 arrays with every element equal to 0, 1, 3 or 5 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero.at n=7A302430
- Numbers m such that m^2+1 is semiprime with (m-1)^2+1 and (m+1)^2+1 primes.at n=29A321985
- Squarefree numbers k such that the sum of the distinct prime factors of k is twice the difference between the largest and the smallest prime factors of k.at n=16A324210
- Number of partitions of n such that 4*(least part) + 1 = greatest part.at n=60A363076
- For n >= 1, a(n) is the least k >= 1 such that 1/d(k) + ... + 1/d(k + n - 1) is an integer, d(i) = A000005(i).at n=53A366048