13905
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 18
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 16
- Divisor Sum
- 24960
- Proper Divisor Sum (Aliquot Sum)
- 11055
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 7344
- Möbius Function
- 0
- Radical
- 1545
- Omega Function (Ω)
- 5
- 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
- 89
- Smith Number
- yes
- 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
- no
- Odd
- yes
Appears in sequences
- Euler transform of A027656(n-1).at n=29A035528
- Numbers n such that 6n+5, 6n+11, 6n+17, 6n+23 are consecutive primes or 6n+1, 6n+7, 6n+13, 6n+19 are consecutive primes.at n=29A090833
- Numbers k such that 6*k+1, 6*k+7, 6*k+13, 6*k+19 are consecutive primes.at n=14A090839
- Numbers k for which nontrivial positive magic squares of exactly 9 different orders with magic sum k exist. For a definition of nontrivial positive magic squares, see A125005.at n=30A125016
- Q(n,6), where Q(m,k) is defined in A127080 and A127137.at n=33A127148
- Number of n X n binary arrays symmetric under 180 degree rotation with all ones connected only in a 5-point barb 1,1 1,2 2,2 2,3 3,2 in any orientation.at n=8A146143
- Deficient numbers n having a companion m > n such that sigma(n)/n = sigma(m)/m.at n=24A212608
- Hilltop maps: number of n X 2 binary arrays indicating the locations of corresponding elements not exceeded by any king-move neighbor in a random 0..1 n X 2 array.at n=6A218657
- Hilltop maps: number of nX7 binary arrays indicating the locations of corresponding elements not exceeded by any king-move neighbor in a random 0..1 nX7 array.at n=1A218662
- T(n,k) = Hilltop maps: number of n X k binary arrays indicating the locations of corresponding elements not exceeded by any king-move neighbor in a random 0..1 n X k array.at n=29A218663
- T(n,k) = Hilltop maps: number of n X k binary arrays indicating the locations of corresponding elements not exceeded by any king-move neighbor in a random 0..1 n X k array.at n=34A218663
- Numbers n such that n*8^n - 1 is prime.at n=14A242201
- Egyptian fraction representation of sqrt(46) (A010500) using a greedy function.at n=4A248272
- Coefficients in asymptotic expansion of sequence A225960.at n=7A260957
- Duplicate of A090839.at n=14A296055
- Number of equivalence classes of binary words of length n for the subword 10110.at n=31A317669
- Numbers k such that iphi(k) = iphi(k+1), where iphi(k) is an infinitary analog to the Euler totient function (A091732).at n=20A326403
- Number of binary necklaces with n beads and at least four consecutive black beads.at n=18A351361
- a(0..4) = 1 and a(n) = (a(n-2)^2 + a(n-3)^2 + a(n-2)*(3*a(n-3) + a(n-4)) + a(n-1)*(a(n-3) - a(n-5)))/(a(n-4) + a(n-5)) for n > 4.at n=12A376024
- Irregular triangle read by rows: T(n,k) is the number of polyominoes of size k, i.e., connected subsets of k square cells (or vertices), of the n X n flat torus, up to cyclic shifts and reflections of rows and columns; 1 <= k <= n^2.at n=41A385383