13081
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 13
- Digital Root
- 4
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 13312
- Proper Divisor Sum (Aliquot Sum)
- 231
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 12852
- Möbius Function
- 1
- Radical
- 13081
- 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
- 169
- 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
- Numbers k such that 1^5 + 2^5 + ... + k^5 is a square.at n=4A031138
- Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 66 ones.at n=13A031834
- a(n) = n-th prime number * n-th lucky number.at n=26A032601
- Multiplicity of highest weight (or singular) vectors associated with character chi_155 of Monster module.at n=39A034543
- a(n) = (n-1)! * Sum_{k=1..n} k^k/k!.at n=5A054201
- a(n) = sum of absolute-valued coefficients of (1+2*x-2*x^2)^n.at n=7A084777
- Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, 0, 0), (-1, 1, 1), (0, -1, 1), (0, 1, -1), (1, 0, 1)}.at n=8A149449
- a(n) = 8*n^2 + 7*n + 1.at n=40A194268
- a(n) = 1 + n + ((n-1)*n^2)/2.at n=30A218152
- Values of n such that L(14) and N(14) are both prime, where L(k) = (n^2+n+1)*2^(2*k) + (2*n+1)*2^k + 1, N(k) = (n^2+n+1)*2^k + n.at n=35A227517
- Smallest odd number expressible in exactly n ways as p + 2*m^2 where p is 1 or a prime and m >= 0.at n=43A228466
- Semiprimes whose prime factors are of equal binary length and which differ from each other in exactly two bit positions.at n=39A261074
- Sequence of pairwise relatively prime numbers of class P_7 (see comment in A275246).at n=14A275252
- a(n) = Sum_{d|n} d^2 * (d+1)/2.at n=27A278403
- Numbers k such that (26*10^k + 49)/3 is prime.at n=20A282536
- a(n) = (1/2)*A293077(n).at n=18A293078
- Irregular triangle T(n,c) read by rows: the number of clusters of n spheres centered on f.c.c. lattice sites with c contacts.at n=62A300812