1911
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 12
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 12
- Divisor Sum
- 3192
- Proper Divisor Sum (Aliquot Sum)
- 1281
- 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
- 1008
- Möbius Function
- 0
- Radical
- 273
- 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
- 29
- 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
- no
- Odd
- yes
Appears in sequences
- a(n) = sigma_2(n): sum of squares of divisors of n.at n=35A001157
- Number of cells of square lattice of edge 1/n inside quadrant of unit circle centered at 0.at n=49A001182
- Heptagonal (or 7-gonal) pyramidal numbers: a(n) = n*(n+1)*(5*n-2)/6.at n=13A002413
- Numbers k such that (k^2 + k + 1)/19 is prime.at n=42A002643
- a(n) = solution to the postage stamp problem with n denominations and 7 stamps.at n=7A005342
- Coordination sequence T3 for Zeolite Code MFS.at n=27A008175
- Coordination sequence T7 for Zeolite Code PAU.at n=32A008225
- Year of birth of n-th President of U.S.A.at n=39A008745
- Numbers k that divide s(k), where s(1)=1, s(j)=9*s(j-1)+j.at n=18A014857
- Integers k such that k divides 22^k - 1.at n=28A014959
- Expansion of g.f. 1/(1 - x^7 - x^8 - x^9 - x^10 - x^11).at n=53A017860
- Powers of cube root of 17 rounded to nearest integer.at n=8A018025
- Powers of cube root of 17 rounded up.at n=8A018026
- Inverse Euler transform of A000931.at n=39A018243
- Records in A019294, number of iterations of the sigma function to reach a multiple of the starting value.at n=23A019277
- Fibonacci sequence beginning 4, 19.at n=11A022135
- Describe previous term from the right (method A - initial term is 9).at n=2A022513
- Expansion of Product_{m >= 1} (1-m*q^m)^13.at n=6A022673
- Numbers k such that Fib(k) == 13 (mod k).at n=16A023178
- Numbers with exactly 9 ones in binary expansion.at n=30A023691