1918
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 19
- Digital Root
- 1
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 3312
- Proper Divisor Sum (Aliquot Sum)
- 1394
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Highly Composite
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 816
- Möbius Function
- -1
- Radical
- 1918
- Omega Function (Ω)
- 3
- 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
- 130
- 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
- yes
- Odd
- no
Appears in sequences
- Number of ways of placing n labeled balls into 3 indistinguishable boxes with at least 2 balls in each box.at n=3A000478
- S2(j,2j+3) where S2(n,k) is a 2-associated Stirling number of the second kind.at n=2A000504
- Heptagonal numbers (or 7-gonal numbers): n*(5*n-3)/2.at n=28A000566
- Number of permutations p of {1,2,...,n} such that p(i) - i < 0 or p(i) - i > 2 for all i.at n=8A001887
- Coordination sequence T3 for Zeolite Code AFT.at n=33A008028
- Coordination sequence T2 for Zeolite Code EMT.at n=36A008087
- Coordination sequence T2 for Zeolite Code GOO.at n=30A008112
- Coordination sequence T3 for Zeolite Code GOO.at n=30A008113
- Coordination sequence T1 for Zeolite Code PAU.at n=32A008219
- Triangle T(n,k) of associated Stirling numbers of second kind, n >= 2, 1 <= k <= floor(n/2).at n=18A008299
- Expansion of (1+x^7)/((1-x)*(1-x^2)*(1-x^3)*(1-x^4)).at n=50A008768
- Expansion of Product (1 - x^k)^10 in powers of x.at n=40A010818
- Even heptagonal numbers (A000566).at n=14A014640
- Seidel's triangle, read by rows.at n=33A014781
- Population of "Triangle" cellular automaton at n-th generation.at n=24A018189
- a(n) = a(n-1) + a(n-2) + 1, with a(0) = 1 and a(1) = 6.at n=13A022320
- Numbers with exactly 9 ones in binary expansion.at n=33A023691
- a(n) = s(1)t(n) + s(2)t(n-1) + ... + s(k)t(n+1-k), where k = [ (n+1)/2 ], s = A014306, t = (primes).at n=39A024696
- a(n) = least m such that if r and s in {1/1, 1/3, 1/5, ..., 1/(2n-1)} satisfy r < s, then r < k/m < (k+4)/m < s for some integer k.at n=14A024847
- a(n) = a(1)*a(n-1) + a(2)*a(n-2) + ... + a(n-3)*a(3) for n >= 4, with initial terms 2, -2, 1, 2.at n=14A025260