8720
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 17
- Digital Root
- 8
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 20
- Divisor Sum
- 20460
- Proper Divisor Sum (Aliquot Sum)
- 11740
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Highly Composite
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 3456
- Möbius Function
- 0
- Radical
- 1090
- Omega Function (Ω)
- 6
- 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
- 47
- 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
- Numbers n such that n is a substring of its square (both n and n squared in base 4) (written in base 10).at n=24A018828
- a(n) = n*(17*n + 1)/2.at n=32A022275
- Numbers k such that k divides the (left) concatenation of all numbers <= k written in base 9 (most significant digit on right and removing all least significant zeros before concatenation).at n=8A029526
- Sum of consecutive nonsquares.at n=16A048395
- Number of n-bead necklace structures using a maximum of five different colored beads.at n=9A056293
- a(n) is the total squared perimeter of all self-avoiding polygons of area n on the square lattice.at n=4A056633
- Numbers n such that phi(n) is the sum of the first k divisors of n for some k.at n=18A072278
- Numbers n such that ((n-1)^2+1)/2 and n^2+1 and ((n+1)^2+1)/2 are prime if n is even or (n-1)^2+1 and (n^2+1)/2 and (n+1)^2+1 are prime if n is odd.at n=41A082612
- Numbers k for which 8*k+1, 8*k+3 and 8*k+7 are primes.at n=44A123978
- A000012 * A122890.at n=41A135722
- a(n)=0^n+sum{k=0..n-1, C(n+k-1,2k)*A000108(k)*3^k*2^(n-k)}.at n=5A152600
- a(n) = 512n + 16.at n=16A157475
- a(n) = 441*n^2 - 488*n + 135.at n=4A157730
- prime(n)*( prime(n)-n ).at n=28A161522
- Number of ways to place 3 nonattacking knights on a 3 X n board.at n=13A172212
- a(1)=1. a(n) = A005179(d(a(n-1))) + a(n-1), where d(n) = the number of divisors of n, and A005179(n) is the smallest positive integer with exactly n divisors.at n=38A175300
- Base-6 Keith numbers.at n=14A188197
- Row sums of the triangle in A199332.at n=31A199771
- Number of 0..n arrays x(0..2) of 3 elements with each no smaller than the sum of its previous elements modulo (n+1).at n=30A200252
- Number of 0..3 arrays x(0..n-1) of n elements with nondecreasing average value.at n=10A200759