12905
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 17
- Digital Root
- 8
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 16200
- Proper Divisor Sum (Aliquot Sum)
- 3295
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 9856
- Möbius Function
- -1
- Radical
- 12905
- 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
- 169
- 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
- Pseudoprimes to base 12.at n=37A020140
- a(1) = 7; a(n+1) = a(n)-th nonprime, where nonprimes begin at 1.at n=34A025006
- [ Sum{(sqrt(j+1)-sqrt(i+1))^3} ], 1 <= i < j <= n.at n=42A025223
- Number of partitions of n into parts not of the form 13k, 13k+6 or 13k-6. Also number of partitions with at most 5 parts of size 1 and differences between parts at distance 5 are greater than 1.at n=39A035954
- Pair the odd numbers such that the k-th pair is (r, r+2k) where r is the smallest odd number not included earlier: (1, 3), (5, 9), (7, 13), (11, 19), (15, 25), (17, 29), (21, 35), (23, 39), (27, 45), ... This is the sequence of the product of the members of pairs.at n=27A075320
- Smallest multiple of n that begins with the concatenation of the divisors of n (in increasing order).at n=28A078218
- a(n) = 25*n^2 - 14*n + 2.at n=23A154357
- Beach-Williams Pell numbers of type pqr (p,q,r primes).at n=0A212079
- Products of 3 evil primes (A027699) p,q,r, such that numbers p*q, p*r, q*r, and p*q*r are odious (A000069).at n=18A230353
- Free polyominoes with 2n squares, having 180-degree rotational symmetry about a square mid-side, but no reflective symmetry.at n=8A234008
- Number of isosceles triangles, distinct up to congruence, on a centered hexagonal grid of size n.at n=47A241237
- a(n) = p(2,n), where p(x,n) is the strong divisibility sequence of polynomials based on sqrt(6) as in A327323.at n=3A329016
- a(n) is the smallest nonnegative integer such that the sum of any five ordered terms a(k), k<=n (repetitions allowed), is unique.at n=9A365301
- Composite numbers in A381019 which are immediately followed by another composite number, in order of their appearance.at n=35A379810
- Expansion of (1-x^2) / (1-x-3*x^2+x^3).at n=13A382683