15420
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 12
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 24
- Divisor Sum
- 43344
- Proper Divisor Sum (Aliquot Sum)
- 27924
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 4096
- Möbius Function
- 0
- Radical
- 7710
- Omega Function (Ω)
- 5
- 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
- yes
- Narcissistic Number
- no
- Collatz Steps
- 53
- 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 Hamiltonian paths in W_4 X P_n.at n=3A003766
- Numbers whose base-4 representation contains exactly three 0's and four 3's.at n=12A045080
- Numbers k such that sigma(phi(k)) is a prime.at n=33A062514
- a(n) is the position of A050614(n) in A062877.at n=13A062878
- Solutions to phi(gpf(x)) - gpf(phi(x)) = 254 = c are special multiples of 257, x = 257k, where largest prime factors of factor k were observed from {2, 3, 5, 17}. See solutions to other even cases of c (=A070813): A007283 for 0, A070004 for 2, A070814 for 14, A070816 for 65534.at n=20A070815
- List of codewords in binary lexicode with Hamming distance 8 written as decimal numbers.at n=6A075940
- Numbers k such that phi(k) is a perfect sixth power.at n=22A078166
- Integers i such that 9*i = 25 X i, but 17*i is not 49 X i.at n=19A115811
- Numbers n that raised to the powers from 1 to k (with k>=1) are multiple of the sum of their digits (n raised to k+1 must not be a multiple). Case k=10.at n=23A135195
- G.f. is the polynomial (1-x^3) * (1-x^6) * (1-x^9) * (1-x^12) * (1-x^15) * (1-x^18) / (1-x)^6.at n=20A162539
- G.f. is the polynomial (1-x^3) * (1-x^6) * (1-x^9) * (1-x^12) * (1-x^15) * (1-x^18) / (1-x)^6.at n=37A162539
- a(n) = n*(2*n^2 + 5*n + 13)/2.at n=24A163655
- Triangle read by rows: T(n,k) is the number of permutations of [n] having k cycles with at least 3 alternating runs (it is assumed that the smallest element of a cycle is in the first position), 0<=k<=floor(n/4).at n=12A187250
- Number of permutations of [n] having no cycle with 3 or more alternating runs (it is assumed that the smallest element of a cycle is in the first position).at n=8A187251
- a(n+1) = 2*a(n) + A014017(n+5), a(0) = 0.at n=18A191497
- a(n) = floor((-1 + 4^n)/(-1 + 2*n)).at n=8A191636
- Triangle read by rows, arising in enumeration of permutations by cyclic valleys, cycles and fixed points.at n=13A216964
- Triangle read by rows, related to Bell numbers A000110: A216962 interlaced with A216964.at n=29A217204
- Number of nX4 0..1 arrays with exactly floor(nX4/2) elements unequal to at least one horizontal, diagonal or antidiagonal neighbor, with new values introduced in row major 0..1 order.at n=6A222505
- T(n,k)=Number of nXk 0..1 arrays with exactly floor(nXk/2) elements unequal to at least one horizontal, diagonal or antidiagonal neighbor, with new values introduced in row major 0..1 order.at n=51A222509