2178
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 18
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 18
- Divisor Sum
- 5187
- Proper Divisor Sum (Aliquot Sum)
- 3009
- 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
- 660
- Möbius Function
- 0
- Radical
- 66
- 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
- 45
- 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
- Construct a triangle as in A036262. Sequence is one less than the position of the first number larger than 2 in the n-th row (n-th difference).at n=36A000232
- a(n) = 2*n^2.at n=33A001105
- Number of partitions of n into Fibonacci parts (with a single type of 1).at n=44A003107
- Self numbers divisible by sum of their digits (or, self numbers which are also Harshad numbers).at n=48A003219
- a(n) = (n + 1)*(n + 2)*(n + 4)*(n + 8)*(n + 15)/120.at n=7A006636
- Inverse Moebius transform applied twice to squares.at n=37A007433
- Expansion of (x^6-x^5-x^4+2x^2)/((1-x^3)(1-x^2)^2(1-x)).at n=49A007988
- Coordination sequence T1 for Zeolite Code CAS.at n=28A008063
- Coordination sequence T2 for Zeolite Code EDI.at n=33A008085
- Coordination sequence T1 for Zeolite Code GOO.at n=32A008111
- Coordination sequence T1 for Zeolite Code MEL.at n=30A008150
- Coordination sequence T3 for Zeolite Code STI.at n=32A008236
- Theta series of direct sum of 3 copies of hexagonal lattice.at n=9A008654
- Numbers k such that 4*k = (k written backwards), k > 0.at n=0A008918
- Numbers k such that k written backwards is a nontrivial multiple of k.at n=1A008919
- Coordination sequence for NiAs(2), As position.at n=22A009945
- Bisection of A001400.at n=31A014125
- Number of integer points (x,y,z) at distance <= 0.5 from sphere of radius n.at n=13A016728
- Fibonacci sequence beginning 4, 22.at n=11A022385
- Expansion of Product_{m>=1} (1-m*q^m)^-3.at n=7A022727