2159
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 17
- Digital Root
- 8
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 2304
- Proper Divisor Sum (Aliquot Sum)
- 145
- 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
- 2016
- Möbius Function
- 1
- Radical
- 2159
- 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
- yes
- Narcissistic Number
- no
- Collatz Steps
- 125
- 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
- Numbers of the form (p^2 - 1)/120 where p is 1 or prime.at n=46A002381
- Number of n-covers of an unlabeled 3-set.at n=8A005745
- Worst cases for Pierce expansions (numerators).at n=28A006537
- Coordination sequence T2 for Zeolite Code AET.at n=32A008008
- Coordination sequence T1 for Zeolite Code ANA.at n=30A008031
- Coordination sequence T6 for Zeolite Code MEL.at n=30A008155
- Coordination sequence T4 for Zeolite Code PAU.at n=34A008222
- Coordination sequence T4 for Zeolite Code VET.at n=28A009905
- Coordination sequence for Ni2In, Position Ni1 and In.at n=14A009941
- Numbers k such that the period of the continued fraction for sqrt(k) contains exactly three 1's.at n=31A013650
- a(n) = n^2 + 3*n - 1.at n=45A014209
- Number of ordered 5-tuples of integers from [ 2,n ] with no common factors among triples.at n=13A015657
- Odd numbers k such that phi(k) | sigma_3(k).at n=37A015809
- Twelve iterations of Reverse and Add are needed to reach a palindrome.at n=1A015993
- Coordination sequence T7 for Zeolite Code TER.at n=31A016439
- n-th composite is sum of first k composites for some k.at n=45A020642
- a(n) is number of cycles in Moebius ladder M_n.at n=11A020873
- a(n) = n*(15*n - 1)/2.at n=17A022272
- Numbers with exactly 6 2's in their ternary expansion.at n=7A023704
- [ (4th elementary symmetric function of S(n))/(2nd elementary symmetric function of S(n)) ], where S(n) = {first n+3 positive integers congruent to 1 mod 4}.at n=7A024389