17580
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 21
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 24
- Divisor Sum
- 49392
- Proper Divisor Sum (Aliquot Sum)
- 31812
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 4672
- Möbius Function
- 0
- Radical
- 8790
- 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
- yes
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 128
- 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 k such that prime(k) + prime(k+1)*2 is a square.at n=27A064504
- Average of twin-prime pairs for pairs that are expressible as the sum of two triangular numbers.at n=33A117313
- 5 times centered pentagonal numbers: 5*(5*n^2 + 5*n + 2)/2.at n=37A164015
- Least number k >= 0 such that (n!+k)/n is prime.at n=59A245695
- Sum over each antidiagonal of A248011.at n=11A248016
- a(n) = n^3 + 4.at n=26A274077
- a(n) = a(n-1) + 4*a(n-2) - 2*a(n-3), where a(0) = 2, a(1) = 4, a(2) = 8.at n=11A288476
- Number of permutations p of [n] such that 0p has a nonincreasing jump sequence beginning with three.at n=11A292169
- (1/7) times the sum of the elements of all subsets of [n] whose sum is divisible by seven.at n=14A309299
- a(n) = 3*2*1 + 6*5*4 + 9*8*7 + 12*11*10 + ... + (up to the n-th term).at n=21A319867
- Numbers that are not Keith numbers in any base.at n=23A320122
- G.f. A(x) = Sum_{n>=0} a(n)*x^n satisfies: [Sum_{n>=0} x^n/(1 - x^(n+1))]^4 = Sum_{n>=0} a(n)*x^n/(1 - x^(n+1))^4.at n=15A341375
- Midpoints k of a pair of twin primes such that sigma(k) is also the midpoint of a pair of twin primes.at n=29A349981
- Coefficients of the expansion of Sum_{i,j,k>=1} x^(i*j*k)/((1-x^i)*(1-x^j)*(1-x^k)).at n=46A350596