15210
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 9
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 36
- Divisor Sum
- 42822
- Proper Divisor Sum (Aliquot Sum)
- 27612
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 3744
- Möbius Function
- 0
- Radical
- 390
- Omega Function (Ω)
- 6
- 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
- yes
- Harshad Number
- yes
- Narcissistic Number
- no
- Collatz Steps
- 32
- 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
- a(n) = 10*n^2.at n=39A033583
- Base-7 palindromes that start with 6.at n=32A043020
- Numbers k such that 8*10^k + 7*R_k is prime, where R_k = 11...1 is the repunit (A002275) of length k.at n=15A056724
- Numbers k that divide phi(k)^2 + sigma(k)^2.at n=30A068484
- Numbers k such that sigma(phi(k)) = k-phi(k).at n=3A070171
- Least m such that reverse(sigma(m)) = sigma(m+n).at n=3A071813
- Sum of squares of digits of n is equal to the largest prime factor of n reversed, where the largest prime factor is not a palindrome.at n=24A074303
- a(n) is the square of the n-th partial sum minus the n-th partial sum of the squares, divided by a(n-1), for all n>=1, starting with a(0)=1, a(1)=2.at n=13A087955
- Triangle read by rows: T(n,k) is the number of Motzkin paths of length n having k returns (i.e., down steps hitting the x-axis).at n=50A097612
- Number of partitions of n such that the number of blocks is congruent to 3 mod 4.at n=7A099948
- 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=8.at n=27A135193
- Triangle T(n, k) = S(n, k) + S(n, n-k), where S are the Stirling numbers (A048993) of the second kind, read by rows.at n=58A154844
- Triangle T(n, k) = S(n, k) + S(n, n-k), where S are the Stirling numbers (A048993) of the second kind, read by rows.at n=62A154844
- Half the number of length n integer sequences with sum zero and sum of squares 4232.at n=3A157578
- Number of strings of numbers x(i=1..8) in 0..n with sum i*x(i)^4 equal to 8*n^4.at n=18A184852
- Number of non-monotonic functions from [k] to [n-k].at n=24A189711
- Number of ways to place 3 non-attacking ferses on an n X n board.at n=6A201244
- Numbers m such that the GCD of the x's that satisfy sigma(x) = m is 2.at n=37A241647
- a(n) = Round((gamma^2 + 1)/gamma^(n-2)).at n=19A245531
- Numbers divisible by prime(d) for each digit d in their base-7 representation, none of which may be zero.at n=46A256877