15255
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
- 2
Divisibility
- Divisor Count
- 16
- Divisor Sum
- 27360
- Proper Divisor Sum (Aliquot Sum)
- 12105
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 8064
- Möbius Function
- 0
- Radical
- 1695
- 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
- 84
- 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
- no
- Odd
- yes
Appears in sequences
- a(n) = Sum_{k=1..n} k*phi(k).at n=41A011755
- a(n) = n-th prime number * n-th lucky number.at n=29A032601
- a(n) = (n+1)^2*(n+2)*(5*n^2 + 15*n + 12)/24.at n=8A108676
- Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, 0), (-1, 1, -1), (-1, 1, 0), (1, -1, 0), (1, 0, 1)}.at n=9A148753
- Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, 1), (-1, 0, 1), (-1, 1, -1), (1, 0, -1), (1, 1, 0)}.at n=9A148754
- Deficient numbers n having a companion m > n such that sigma(n)/n = sigma(m)/m.at n=28A212608
- Unchanging value maps: number of nX7 binary arrays indicating the locations of corresponding elements unequal to no horizontal, diagonal or antidiagonal neighbor in a random 0..2 nX7 array.at n=2A219141
- T(n,k)=Unchanging value maps: number of nXk binary arrays indicating the locations of corresponding elements unequal to no horizontal, diagonal or antidiagonal neighbor in a random 0..2 nXk array.at n=38A219142
- Unchanging value maps: number of 3Xn binary arrays indicating the locations of corresponding elements unequal to no horizontal, diagonal or antidiagonal neighbor in a random 0..2 3Xn array.at n=6A219144
- Unmatched value maps: number of nX7 binary arrays indicating the locations of corresponding elements not equal to any horizontal, diagonal or antidiagonal neighbor in a random 0..1 nX7 array.at n=2A219440
- T(n,k)=Unmatched value maps: number of nXk binary arrays indicating the locations of corresponding elements not equal to any horizontal, diagonal or antidiagonal neighbor in a random 0..1 nXk array.at n=38A219441
- Product of n and the sum of remainders of n mod k, for k = 1, 2, 3, ..., n.at n=44A256532
- 37-gonal numbers: a(n) = n*(35*n-33)/2.at n=30A282852
- Let a(0)=1. Then a(n) = sums of consecutive strings of positive integers of length 3*n, starting with the integer 2.at n=15A289721
- Indices k of highly composite numbers with records of low values of the ratio between consecutive terms, A002182(k+1)/A002182(k).at n=17A309745
- One of the two successive approximations up to 13^n for 13-adic integer sqrt(-3). Here the 6 (mod 13) case (except for n = 0).at n=4A322089
- G.f.: Sum_{n>=0} (n+1)*(n+2)/2 * x^n * (1 + x^n)^n.at n=58A326003
- a(n) = Sum_{i=1..n, gcd(i,n)=1} i*phi(i) where phi is Euler's totient function A000010.at n=42A333291
- Irregular triangle read by rows: T(n,k) (n >= 1, 0 <= k <= (n-1)*(n-2)/2) = number of weakly connected subdigraphs of the transitive tournament on n nodes that have k arcs.at n=39A350610