13420
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 10
- Digital Root
- 1
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 24
- Divisor Sum
- 31248
- Proper Divisor Sum (Aliquot Sum)
- 17828
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 4800
- Möbius Function
- 0
- Radical
- 6710
- Omega Function (Ω)
- 5
- Little Omega Function (ω)
- 4
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
- yes
- Narcissistic Number
- no
- Collatz Steps
- 94
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- Squarefree Number
- no
- 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
- yes
- Odd
- no
Appears in sequences
- Fibonacci sequence beginning 0, 22.at n=15A022356
- Positive numbers k such that k and 2*k are anagrams in base 6 (written in base 6).at n=9A023064
- a(n) = (2*n+1)*(9*n+1).at n=27A033573
- a(n) = Sum{a(k): k=0,1,2,...,n-4,n-2,n-1}; a(n-3) is not a summand; initial terms are 1,2,2.at n=16A049868
- (1/18)*Difference between concatenation of n and n^2 and concatenation of n^2 and n.at n=39A055435
- Coefficients in expansion of Sum_{n >= 1} x^n/(1-x^n)^4.at n=40A059358
- Number of degree-n even permutations of order dividing 10.at n=9A061132
- Ooguri-Vafa invariants of disk domain wall degeneracies for brane I in the O(K) -> P^1 X P^1 geometry.at n=2A061611
- Numbers k such that the period of the continued fraction for sqrt(5)*k is 2.at n=34A065030
- Final members of groups in A076105.at n=40A076102
- Numbers k such that iterating phi(sigma(k)-phi(k)) starting from k leads to the fixed point 8064.at n=28A077096
- Numbers whose set of base 11 digits is {0,A}, where A base 11 = 10 base 10.at n=10A097257
- Numbers k such that 3^k mod k = 3^k mod k^2.at n=23A125774
- Numbers k such that k^2 divides 9^k - 1.at n=33A127101
- Numbers k such that k^2 divides 3^k-1.at n=8A127103
- Numbers k such that k^3 divides 3^(k^2) - 1.at n=34A129211
- Sequence representing valid nontrivial 1-dimensional Hashi (a.k.a. Bridges or Hashiwokakero) puzzle orientations.at n=35A143964
- Number of walks within N^2 (the first quadrant of Z^2) starting at (0,0), ending on the vertical axis and consisting of n steps taken from {(-1, -1), (-1, 0), (0, 1), (1, 0)}.at n=10A151386
- Number of ways that a 1 X n rectangular tile T, marked into n unit squares, can be surrounded by one layer of copies of itself laid in the plane grid generated by the units of T. Ways that differ by rotation or reflection are not counted as different. The surrounded tile is the exact surrounded region.at n=14A159294
- Recurrence a(n)*a(n-2) = a(n-1)*(a(n-1) + 3) with a(0) = 1, a(1) = 4.at n=5A182432