2191
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 13
- Digital Root
- 4
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 2512
- Proper Divisor Sum (Aliquot Sum)
- 321
- 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
- 1872
- Möbius Function
- 1
- Radical
- 2191
- Omega Function (Ω)
- 2
- Little Omega Function (ω)
- 2
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
- 76
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- yes
- 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
- Number of permutations of (1,...,n) having n-2 inversions (n>=2).at n=7A001892
- Numbers k such that 21*2^k - 1 is prime.at n=20A002238
- Glaisher's function T_1(n).at n=3A002615
- Numbers that are the sum of 7 positive 6th powers.at n=21A003363
- Numbers that are the sum of 5 positive 7th powers.at n=6A003372
- Numbers that are the sum of at most 5 positive 7th powers.at n=25A004867
- Numbers that are the sum of at most 6 positive 7th powers.at n=32A004868
- Numbers that are the sum of at most 7 positive 7th powers.at n=40A004869
- Numbers that are the sum of at most 8 positive 7th powers.at n=49A004870
- Number of corners, or planar partitions of n with only one row and one column.at n=15A006330
- Number of connected vertex-transitive graphs with n nodes.at n=30A006800
- Coordination sequence T3 for Zeolite Code NON.at n=28A008214
- Triangle of Mahonian numbers T(n,k): coefficients in expansion of Product_{i=0..n-1} (1 + x + ... + x^i), where k ranges from 0 to A000217(n-1). Also enumerates permutations by their major index.at n=121A008302
- Triangle of Mahonian numbers T(n,k): coefficients in expansion of Product_{i=0..n-1} (1 + x + ... + x^i), where k ranges from 0 to A000217(n-1). Also enumerates permutations by their major index.at n=99A008302
- Number of necklaces of sets of beads containing a total of n beads.at n=14A008965
- Coordination sequence T2 for Zeolite Code CON.at n=33A009869
- Positive integers n such that 2^n == 2^7 (mod n).at n=52A015927
- Pseudoprimes to base 99.at n=28A020227
- Numbers k such that the continued fraction for sqrt(k) has period 36.at n=25A020375
- Fibonacci sequence beginning 1, 24.at n=11A022394