2120
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 5
- Digital Root
- 5
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 16
- Divisor Sum
- 4860
- Proper Divisor Sum (Aliquot Sum)
- 2740
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Highly Composite
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 832
- Möbius Function
- 0
- Radical
- 530
- Omega Function (Ω)
- 5
- 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
- yes
- Narcissistic Number
- no
- Collatz Steps
- 125
- 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
- yes
- Odd
- no
Appears in sequences
- Fine's sequence (or Fine numbers): number of relations of valence >= 1 on an n-set; also number of ordered rooted trees with n nodes having root of even degree.at n=10A000957
- Numbers k such that (k^2 + k + 1)/19 is prime.at n=47A002643
- Least positive unitary linear combination of distinct numbers in row n of Pascal's triangle; i.e., least positive sum of form d(0)C(n-1,0) + d(1)C(n-1,1) + ...+ d(m)C(n-1,m), d(i)=+-1, m = floor((n+1)/2).at n=22A004795
- Number of fountains of n coins.at n=16A005169
- Coordination sequence T5 for Zeolite Code DDR.at n=29A008075
- Expansion of sin(x)*cosh(log(1+x)).at n=7A009537
- Coordination sequence T2 for Zeolite Code RTH.at n=32A009894
- Representation of n in base of Catalan numbers (a classic greedy version).at n=37A014418
- Expansion of 1/(1-x^5-x^6-x^7-x^8-x^9-x^10-x^11).at n=37A017842
- Base 6 expansion uses each positive digit just once.at n=9A023744
- n written in fractional base 3/2.at n=12A024629
- a(n) = position of n^2 + (n+1)^2 + (n+2)^2 in A004432.at n=28A024809
- a(1) = 5; a(n+1) = a(n)-th nonprime, where nonprimes begin at 4.at n=21A025010
- a(n) = dot_product(1,2,...,n)*(6,7,...,n,1,2,3,4,5).at n=14A026046
- a(n) = self-convolution of row n of array T given by A026148.at n=5A027329
- Numbers k such that the continued fraction for sqrt(k) has even period and if the last term of the periodic part is deleted the central term is 23.at n=10A031521
- Numbers k such that the least term in the periodic part of the continued fraction for sqrt(k) is 23.at n=1A031701
- Numbers k such that A102489(k) is divisible by k.at n=14A032563
- a(n) = (3*n+1)*(4*n+1).at n=13A033577
- Number of n-step self-avoiding walks on the 4-dimensional hypercubic lattice with no non-contiguous adjacencies.at n=4A034006