13391
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
- 2
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 15312
- Proper Divisor Sum (Aliquot Sum)
- 1921
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 11472
- Möbius Function
- 1
- Radical
- 13391
- 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
- 45
- 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 Fib(k) == -13 (mod k).at n=43A023167
- Row sums of triangle K(m, n), inverse to triangle T(m,n) in A020921.at n=13A038200
- Starting index of a string of 4 or more consecutive equal digits in decimal expansion of Pi.at n=12A049516
- Starting index of a string of exactly 4 consecutive equal digits in decimal expansion of Pi.at n=9A049520
- Starting positions of strings of 3 0's in the decimal expansion of Pi.at n=9A050202
- Multiplicity of irreducible character IRR2 of Monster simple group in n-th head character.at n=31A055771
- Column 3 of triangle A055898.at n=10A055899
- Triangle Q, read by rows, such that Q^3 transforms column k of Q^2 into column k+1 of Q^2, so that column k of Q^2 equals column 0 of Q^(3*k+2), where Q^3 denotes the matrix cube of Q.at n=32A113381
- Triangle, read by rows, given by the product R^3*Q^-2 using triangular matrices Q=A113381, R=A113389.at n=24A114154
- Triangle, read by rows, given by the product Q^-2*P^3 using triangular matrices P=A113370, Q=A113381.at n=41A114155
- Expansion of 1/(1 - x - x^2 + x^4 - x^6).at n=24A117791
- Numbers k such that k and k^2 use only the digits 1, 3, 7, 8 and 9.at n=5A137043
- The Riordan square of the Bell numbers. Triangle T(n, k), 0 <= k <= n, read by rows.at n=48A154380
- Number of (w,x,y,z) with all terms in {1,...,n} and w=x+2y+3z-n.at n=44A212254
- Number of (w,x,y,z) with all terms in {0,...,n} and max{w,x,y,z}>=2*min{w,x,y,z}.at n=10A212741
- Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 161", based on the 5-celled von Neumann neighborhood.at n=28A270452
- Number of n X 2 0..1 arrays with each 1 horizontally, vertically or antidiagonally adjacent to 2 or 3 neighboring 1s.at n=10A296399
- Take a squarefree semiprime and take the difference of its prime factors. If it is a squarefree semiprime repeat the process. Sequence lists the squarefree semiprimes that generate other squarefree semiprimes only in the first k steps of this process. Case k = 4.at n=24A296811
- Take a squarefree semiprime and take the difference of its prime factors. If it is a squarefree semiprime repeat the process. Sequence lists the squarefree semiprimes that generate other squarefree semiprimes only in the first k steps of this process. Case k = 5.at n=5A296812
- Table read by antidiagonals: T(n,k) is the number of paths in the Z X Z grid joining (0,0) and (n,k) each of whose steps increases the Euclidean distance to the origin and has coordinates with absolute value at most 1.at n=29A346538