2091
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
- 8
- Divisor Sum
- 3024
- Proper Divisor Sum (Aliquot Sum)
- 933
- 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
- 1280
- Möbius Function
- -1
- Radical
- 2091
- 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
- yes
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 37
- 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
- a(n) = a(n-2) + a(n-3) + a(n-4), with initial values a(0) = 0, a(1) = 2, a(2) = 3, a(3) = 6.at n=19A001634
- Number of nonequivalent dissections of an n-gon into 3 polygons by nonintersecting diagonals up to rotation and reflection.at n=33A003453
- Divisors of 2^40 - 1.at n=40A003546
- Least positive integer k such that the fractional part of k*sqrt(5) has its n initial partial quotients all equal to 1.at n=7A004794
- Least positive integer k such that the fractional part of k*sqrt(5) has its n initial partial quotients all equal to 1.at n=8A004794
- a(n) = round(n*phi^10), where phi is the golden ratio, A001622.at n=17A004945
- a(n) = ceiling(n*phi^10), where phi is the golden ratio, A001622.at n=17A004965
- a(n) = Sum_{k=0..floor(n/4)} binomial(n-2k,2k).at n=18A005252
- Number of non-Abelian metacyclic groups of order 2^n.at n=41A007982
- Coordination sequence T3 for Zeolite Code -WEN.at n=33A009864
- Coordination sequence T2 for Zeolite Code AHT.at n=31A009867
- Number of ordered triples of integers from [ 2,n ] with no global factor.at n=23A015633
- Positive integers n such that 2^n == 2^11 (mod n).at n=39A015935
- Smallest k>2^n such that 2^k == 2^n (mod k).at n=10A015938
- Pseudoprimes to base 16.at n=26A020144
- Pseudoprimes to base 86.at n=21A020214
- Coordination sequence T1 for Zeolite Code IFR.at n=32A024982
- Sum of numbers between the two n's in A026272.at n=42A026275
- Odd numbers to the left of the central elements of the (2,3)-Pascal triangle A029600.at n=40A029612
- Odd numbers to right of central elements of the (3,2)-Pascal triangle A029618.at n=39A029634