12771
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 18
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 4
Divisibility
- Divisor Count
- 16
- Divisor Sum
- 21120
- Proper Divisor Sum (Aliquot Sum)
- 8349
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 7560
- Möbius Function
- 0
- Radical
- 1419
- Omega Function (Ω)
- 5
- 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
- 125
- Smith Number
- yes
- 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 partitions of 5n such that cn(1,5) = cn(4,5) < cn(0,5) < cn(2,5) = cn(3,5).at n=13A036894
- p^2 + 2 where p is a prime.at n=29A061725
- Numbers n such that phi(2n+1) = sigma(n).at n=35A067229
- Iccanobirt prime indices (10 of 15): Indices of prime numbers in A102120.at n=15A102140
- Number of n X n binary arrays symmetric under 180 degree rotation with all ones connected only in a 2X4 el 1,1 1,2 1,3 1,4 2,4 with any orientation.at n=8A146022
- 3 times 10-gonal (or decagonal) numbers: a(n) = 3*n*(4*n-3).at n=33A152767
- Positive integers that are palindromes (of even length) in binary, each made by concatenating two identical binary palindromes.at n=18A161400
- Let i be in {1,2,3,4} and let r >= 0 be an integer. Let p = {p_1, p_2, p_3, p_4} = {-2,0,1,2}, n=3*r+p_i, and define a(-2)=0. Then a(n)=a(3*r+p_i) gives the quantity of H_(9,2,0) tiles in a subdivided H_(9,i,r) tile after linear scaling by the factor Q^r, where Q=sqrt(x^2-1) with x=2*cos(Pi/9).at n=36A187500
- Total sum of Fibonacci parts in all partitions of n.at n=22A199936
- Numbers whose binary representation is palindromic and in which all runs of 0's and 1's have length at least 2.at n=42A222813
- Sum of the two smallest parts from the partitions of 4n into 4 parts with smallest part = 1.at n=26A239059
- Number of nX3 0..1 arrays with no 1 equal to more than three of its king-move neighbors.at n=4A282394
- Number of n X 5 0..1 arrays with no 1 equal to more than three of its king-move neighbors.at n=2A282396
- T(n,k)=Number of nXk 0..1 arrays with no 1 equal to more than three of its king-move neighbors.at n=23A282399
- T(n,k)=Number of nXk 0..1 arrays with no 1 equal to more than three of its king-move neighbors.at n=25A282399
- Numbers k such that (35*10^k - 593)/9 is prime.at n=18A290964
- Numbers k such that 4*10^k + 91 is prime.at n=16A295030
- Numbers k such that A307437(k) is divisible by 3.at n=17A342037
- a(n) = Sum_{k=0..floor(n/6)} (-1)^k * binomial(n-3*k,3*k).at n=26A348308
- Numbers whose base-2 representation is a "nested" palindrome.at n=41A373941