12945
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
- 2
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 20736
- Proper Divisor Sum (Aliquot Sum)
- 7791
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 6896
- Möbius Function
- -1
- Radical
- 12945
- Omega Function (Ω)
- 3
- 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
- 125
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- Squarefree Number
- yes
- 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
- Positions of remoteness 4 in Beans-Don't-Talk.at n=30A005696
- Number of points on surface of tricapped prism: a(n) = 7*n^2 + 2 for n > 0, a(0)=1.at n=43A005919
- Numbers whose sum of divisors is a fourth power.at n=32A019422
- a(n) = s(1)t(n) + s(2)t(n-1) + ... + s(k)t(n+1-k), where k = [ (n+1)/2 ], s = (composite numbers), t = (odd natural numbers).at n=33A024590
- a(n) = s(1)t(n) + s(2)t(n-1) + ... + s(k)t(n-k+1), where k = [ n/2 ], s = (composite numbers), t = (odd natural numbers).at n=32A025104
- Numerators of continued fraction convergents to sqrt(749).at n=9A042442
- T(n,n-1), array T as in A047040; T(n-1,n), array T given by A047050.at n=9A047043
- T(n,n-2), array T as in A047040; T(n-2,n), array T given by A047050.at n=9A047044
- Exponents in expansion of rank-2 Artin constant product(1-1/(p^3-p^2), p=prime) as a product zeta(n)^(-a(n)).at n=33A065417
- Triangle read by rows, where t(n,1) = 1, t(n,m) = t(n,m-1) + (largest nonprime {1 or composite} in row {n-1}).at n=44A120853
- Number of admissible sequences of order j; related to 5x+1 problem.at n=8A174795
- Number of length n+4 0..1 arrays with at most one downstep in every n consecutive neighbor pairs.at n=37A255995
- G.f.: A(x) = exp( Sum_{n>=1} 5^n * x^n/(n*(1+x^n)) ).at n=6A259275
- Number of ways to write n as an ordered sum of 8 nonprime numbers.at n=24A341485
- a(n) is the number of distinct radii of circles passing through at least three points in a square grid of n X n points.at n=17A357301