13845
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 21
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 16
- Divisor Sum
- 24192
- Proper Divisor Sum (Aliquot Sum)
- 10347
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 6720
- Möbius Function
- 1
- Radical
- 13845
- Omega Function (Ω)
- 4
- 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
- no
- Narcissistic Number
- no
- Collatz Steps
- 151
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- 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
- Take pairs (a, b), sorted on a, such that T(a)+T(b)=concatenation of a and b, where T(k) is the k-th triangular number A000217(k). Sequence gives values of a.at n=24A096031
- Numbers k such that k and 2*k, taken together are pandigital.at n=2A115922
- Triangle T(n,k), 0<=k<=n, read by rows, given by [1,2,3,4,5,6,7,8,9,10,...] DELTA [1,1,6,6,15,15,28,28,...] where DELTA is the operator defined in A084938 .at n=17A130847
- Numbers k such that k and k+1 have 4 distinct prime factors.at n=10A140078
- Odd squarefree numbers n such that the cyclotomic polynomial Phi(n,x) is not coefficient convex.at n=2A146960
- a(1) = 1, and for each k >=2, a(k) is the smallest number n such that n/sin(n) > a(k)/sin(a(k)), so that a(1)/sin(a(1)) > a(2)/sin(a(2)) > ... > a(k)/sin(a(k)) > ...at n=33A172445
- Number of strings of numbers x(i=1..5) in 0..n with sum i*x(i) equal to n*5.at n=17A184705
- Number of connected components over all simple unlabeled graphs with n nodes.at n=8A224031
- The number of P-positions in the game of Nim with up to 5 piles, allowing for piles of zero, such that the number of objects in the largest pile is n.at n=14A241731
- Number of Lyndon-Bell strings of length n.at n=9A254036
- Zeroless numbers n with digits d_1, d_2, ... d_k such that d_1^3 + ... + d_k^3 is a cube.at n=53A254960
- Number of active (ON, black) cells at stage 2^n-1 of the two-dimensional cellular automaton defined by "Rule 443", based on the 5-celled von Neumann neighborhood.at n=6A272226
- Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 566", based on the 5-celled von Neumann neighborhood.at n=32A272989
- Numbers k such that k and k+1 both have 16 divisors.at n=36A274359
- Numbers k such that k and k+1 are the product of exactly four distinct primes.at n=5A318896
- Numbers k such that k and k+1 each have at least 4 distinct prime factors.at n=10A321504
- Setwise difference A340150 \ A340076.at n=31A340151
- a(n) = coefficient of sqrt(3) in the expansion of (2 + sqrt(2) + sqrt(3))^n.at n=7A377111
- Indices where the cumulative sum of sin(2k+1)^(2k+1) reaches a record high value.at n=36A387706