15720
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 15
- Digital Root
- 6
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 32
- Divisor Sum
- 47520
- Proper Divisor Sum (Aliquot Sum)
- 31800
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 4160
- Möbius Function
- 0
- Radical
- 3930
- 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
- 146
- 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) = Sum_{k = 1..n} T(k,k-1), where T is the array defined in A024996.at n=10A026079
- Smallest a(n)>2 such that all integers strictly between a(n)-n and a(n) are composite.at n=36A075741
- a(n) = sigma_3(n) - sigma_1(n).at n=24A092348
- Partial sums of Chebyshev sequence S(n,11) = U(n,11/2) = A004190(n).at n=4A097826
- Number of ways to split 1, 2, 3, ..., 5n into n arithmetic progressions each with 5 terms.at n=12A104431
- Nonnegative integers n such that 11*n^2 + 11*n + 1 is a square.at n=3A105838
- a(0)=1; thereafter a(n)=a(n-1)+a([n/Phi]), where Phi=(1+sqrt(5))/2, the golden ratio.at n=41A131882
- First string of 43 consecutive composite numbers.at n=36A177949
- Smallest number k such that prime(n) divides the n-th divisor of k.at n=30A226101
- Numbers k such that k and k+1 have the same binary XOR of divisors.at n=32A227443
- Numbers k with the property that p = k^2 - 13 and q = k^2 + 13 are consecutive primes.at n=37A248785
- The number of overpartitions of n with restricted odd differences.at n=30A260890
- p*B_(p-1)+1 modulo p^2, where p = prime(n) and B_i denotes the i-th Bernoulli number.at n=31A268000
- Where record values occur in A276781, when starting from A276781(2)=1.at n=37A276782
- a(n) is the smallest integer k > n such that (k+1)(k+2)...(2k-2n+1)/(k(k-1)...(k-n+1)) is an integer.at n=36A290791
- Numbers k such that A127417(k) = 1.at n=27A305162
- Number of (binary) max-heaps on n elements from the set {0,1} containing exactly ten 0's.at n=18A326511
- Numbers k such that A348215(k) = k.at n=25A348216
- The least totient number k with exactly n solutions to the equation phi(x) = k, where all the solutions are nontotient numbers (A007617).at n=20A378510