12913
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 16
- Digital Root
- 7
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 13300
- Proper Divisor Sum (Aliquot Sum)
- 387
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 12528
- Möbius Function
- 1
- Radical
- 12913
- Omega Function (Ω)
- 2
- Little Omega Function (ω)
- 2
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
- 24
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- yes
- 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
- a(n) = [ a(n-1)/a(1) + a(n-2)/a(2) + ... + a(1)/a(n-1) ], for n >= 3.at n=29A022869
- a(1) = 1; a(n) = Sum_{k=1..n-1} a(floor((n-1)/k)).at n=47A078346
- Numbers k such that k! - k# + 1 is prime, where k# is the primorial function.at n=20A081712
- Integer floor of coefficients of exp(x*A(x)).at n=14A085022
- Semiprimes that are the sum of two positive cubes. Common terms of A003325 and A046315.at n=41A085366
- Lengths of successive words (starting with a) under the substitution: {a -> aab, b -> aac, c -> a}.at n=9A101168
- Numbers which are the sum of two positive cubes and divisible by 37.at n=14A102618
- Number of separated bicyclic skeletons with n carbon atoms (see Parks et al. for precise definition).at n=8A121162
- a(n) = n^4 - (n+1)^3.at n=11A178617
- Odd numbers producing 20 even numbers in the Collatz iteration.at n=40A199818
- Number of ordered triples (w,x,y) with all terms in {1,...,n} and 2w^3>x^3+y^3.at n=30A211811
- Total number of parts in all compositions of n with at least two parts in increasing order.at n=12A229935
- a(n) = 2*a(n-1) + 2*a(n-2) + a(n-3). a(0) = -1, a(1) = 1, a(2) = 1.at n=11A233828
- Number of partitions of n such that (greatest part) + (least part) < number of parts.at n=38A237822
- Numbers n such that phi(n) = Sum_{j=1..k} d(n^j) for some k, where phi(n) is the Euler totient function of n and d(n) is the number of divisors of n.at n=31A283757
- Partial sums of A299256.at n=20A299262
- Numbers that are the sum of 4 nonzero 4th powers in more than one way.at n=25A309763
- Number of integer partitions of n > 0 where the maximum part equals the length minus the number of distinct parts.at n=53A324518
- The number of overpartitions of n where the number of non-overlined parts is at least two more than the number of overlined parts.at n=23A340668
- Numbers that are the sum of four fourth powers in exactly two ways.at n=25A344193