11891
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 20
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 13824
- Proper Divisor Sum (Aliquot Sum)
- 1933
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 10120
- Möbius Function
- -1
- Radical
- 11891
- 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
- 50
- 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
- Positive integers k such that k divides 12^k - 1.at n=7A014951
- Numbers k such that k | 10^k + 1.at n=7A015958
- Numbers k that divide 6^k + 5^k.at n=9A045595
- Numbers k such that gcd(3k,8^k+1) = 3 but k does not divide the numerator of B(2k) (the Bernoulli numbers).at n=16A070193
- Orchard crossing number of complete bipartite graph K_{1,n}.at n=46A080838
- a(n) = floor(C(n+6,6)/C(n+2,2)).at n=41A084626
- Structured pentagonal icositetrahedral numbers (vertex structure 13).at n=10A100167
- a(n) = n*(n+13)*(n+14)/6.at n=33A111144
- Numbers k such that k^2 divides 12^k - 1.at n=3A128405
- Numbers k such that k^3 divides 10^(k^2) + 1.at n=3A128683
- 11 times triangular numbers.at n=46A152740
- Products of 3 distinct safe primes.at n=27A157354
- a(n) = n^3 - n*(n+1)/2.at n=23A160378
- Numbers k such that k^3 divides 12^(k^2) - 1.at n=3A177912
- Number of n X 2 0..3 arrays with every row and column nondecreasing rightwards and downwards, and the number of instances of each value within one of each other.at n=42A201445
- Numbers n dividing u(n), where the Lucas sequence is defined u(i) = u(i-1) - 3*u(i-2) with initial conditions u(0)=0, u(1)=1.at n=7A228440
- Squarefree numbers (from A005117) with prime divisors in a 2p+1 progression.at n=11A231966
- Squarefree numbers (A005117) of the form p*q*r with prime factors p, q, r with q = 2*p + 1 and r = 2*q + 1.at n=2A231967
- Numbers whose sum of divisors is equal to the product of the number of divisors of their k first powers, for some k.at n=27A283758
- Numbers k such that k^2 divides 10^k + 1.at n=3A292335