13680
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
- 60
- Divisor Sum
- 48360
- Proper Divisor Sum (Aliquot Sum)
- 34680
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 3456
- Möbius Function
- 0
- Radical
- 570
- Omega Function (Ω)
- 8
- 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
- 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
- Cycle class sequence c(n) (the number of true cycles of length n in which a certain node is included) for zeolite LOV = Lovdarite K4Na12 [Be8Si28O72].18H2O starting with a T3 atom.at n=13A019141
- Number of perfect matchings in graph C_{3} X C_{4} X P_{n}.at n=2A028465
- Number of ways to place a non-attacking white and black king on n X n chessboard.at n=10A035286
- For all n, if d is recursively applied to a(n) exactly 6 times then the fixed point of d-iteration is just reached.at n=14A036458
- Denominators of continued fraction convergents to sqrt(359).at n=7A041681
- Smallest positive number of "triangular" shuffles of n(n+1)/2 cards needed to restore them to their original order.at n=15A048782
- Maximization of sums of cubes of integer differences (b_[ i ]-i)^3 over permutations {b_[ i ], for i-1,2,...,n} on first n integers.at n=24A049031
- Number of strongly triple-free subsets of {1, 2, ..., n}.at n=18A050295
- Freestyle perfect numbers n = Product_{i=1,..,k} f_i^e_i where 1 < f_1 < ... < f_k, e_i > 0, such that 2n = Product_{i=1,..,k} (f_i^(e_i+1)-1)/(f_i-1).at n=44A058007
- Numbers k such that sigma(k) - usigma(k) > 2k.at n=33A063846
- Smallest numbers such that the number of terms in inverse set usigma equals n; where usigma = A034448.at n=33A063975
- Values of m such that N=(am+1)(bm+1)(cm+1) is a 3-Carmichael number (A087788), where a,b,c = 1,2,21.at n=20A064247
- Numbers m such that sigma(4*m+3) = 6*m.at n=5A067678
- Numbers m such that m*tau(m)>5*prime(m).at n=36A068547
- Numbers k such that k-1, k+1 and k^2+1 are prime numbers.at n=27A070155
- Numbers k such that the first k digits of log_10(2) after the decimal point are primes.at n=4A081102
- Numbers k such that binomial(prime(k), k) is divisible by k^2.at n=37A081384
- a(n) = (3*n + 1)*n!.at n=6A082033
- A square array of linear-factorial numbers, read by antidiagonals.at n=51A082037
- Group the natural numbers such that the sum of the terms of every group has a distinct prime signature not occurring earlier: (1), (2), (3, 4, 5), (6), (7, 8, 9), (10, 11, 12, 13, 14), (15, 16, 17), (18, 19, 20, 21)... Sequence contains the sum of the terms of groups.at n=38A086494