13820
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 14
- Digital Root
- 5
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 12
- Divisor Sum
- 29064
- Proper Divisor Sum (Aliquot Sum)
- 15244
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 5520
- Möbius Function
- 0
- Radical
- 6910
- Omega Function (Ω)
- 4
- 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
- 58
- 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
- Closed meandric numbers (or meanders): number of ways a loop can cross a road 2n times.at n=7A005315
- Meandric numbers: number of ways a river can cross a road n times.at n=13A005316
- Dodecahedral surface numbers: a(0)=0, a(1)=1, a(2)=20, thereafter 2*((3*n-7)^2 + 21).at n=30A007589
- Triangle read by rows: T(n,k) = number of closed meander systems of order n with k<=n components.at n=21A008828
- Number of lines through exactly 5 points of an n X n grid of points.at n=46A018812
- Cycle class sequence c(n) (the number of true cycles of length n in which a certain node is included) for zeolite RSN = RUB-17 K4Na12 [ Zn8Si28O72 ]. 18 H2O.at n=13A019222
- [ 4th elementary symmetric function of sqrt(k+1) ], k = 1,2,...,n.at n=7A025221
- n^3*a(n) is the number of circles in complex projective plane tangent to three smooth curves of degree n in general position.at n=22A030653
- Truncated triangular pyramid numbers: a(n) = Sum_{k=4..n} (k*(k+1)/2 - 9).at n=39A051937
- Number of ways that a directed line (or river) that starts in the south can cross an east-west road n times.at n=13A077014
- a(n) is the least positive integer k such that g(k) = n*g(k-1), where g(k) = prime(k+1) - prime(k).at n=29A078563
- Numbers k such that 10^k - 3 is prime.at n=9A089675
- Smallest number that can be written in exactly n ways as a sum of distinct repdigits of its decimal digits.at n=34A131367
- Maximal length of rook tour on an n X n+1 board.at n=26A152132
- Maximal length of rook tour on an n X n+3 board.at n=25A152134
- Number of planar n X n X n binary triangular grids symmetric both under 120-degree rotation and reflection with no more than 1 one in any 4 X 4 X 4 subtriangle.at n=27A153904
- Expansion of (2/(3*sqrt(1-4*z)-1+4*z))*((1-sqrt(1-4*z))/(2*z))^k with k=6.at n=6A172063
- Numbers k that divide the sum of digits of 13^k.at n=34A175525
- Number of generalized mountain numbers (see A134853) with n digits.at n=11A178912
- Coefficient array for square of Chebyshev S-polynomials.at n=78A181878