2180
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 11
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 12
- Divisor Sum
- 4620
- Proper Divisor Sum (Aliquot Sum)
- 2440
- 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
- 864
- Möbius Function
- 0
- Radical
- 1090
- Omega Function (Ω)
- 4
- 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
- no
- 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=34A000232
- Josephus problem: numbers m such that, when m people are arranged on a circle and numbered 1 through m, the final survivor when we remove every 4th person is one of the first three people.at n=21A005427
- Number of points on surface of tetrahedron; coordination sequence for sodalite net (equals 2*n^2+2 for n > 0).at n=33A005893
- Coordination sequence T3 for Zeolite Code CAS.at n=28A008065
- Molien series for A_6.at n=34A008629
- If x and y are terms, so is x*y + 9.at n=18A009350
- Coordination sequence T3 for Zeolite Code VSV.at n=30A009916
- Coordination sequence for NiAs(2), Ni position.at n=22A009946
- a(0) = 1, a(n) = 18*n^2 + 2 for n>0.at n=11A010008
- Number of vectors abcdefg with a,b,... >= 0, a+...+g=n, a>={b,...g}.at n=11A014073
- Expansion of e.g.f. exp(1-x-exp(-x)).at n=10A014182
- Multiplicity of trivial character in V_n, where V = Sum V_n is the graded module for the Monster simple group.at n=30A014810
- Numbers n such that n is a substring of its square when both are written in base 2.at n=35A018826
- Numbers n such that n is a substring of its square (both n and n squared in base 4) (written in base 10).at n=17A018828
- Numbers with exactly 6 2's in their ternary expansion.at n=10A023704
- a(n) = 3^n - n.at n=7A024024
- 3rd elementary symmetric function of C(n,0), C(n,1), ..., C(n,n).at n=3A025131
- a(n) = dot_product(n,n-1,...2,1)*(5,6,...,n,1,2,3,4).at n=15A026060
- a(n) = Sum_{k=0..n} (k+1) * A026648(n,k).at n=8A026975
- "CFJ" (necklace, size, labeled) transform of 1,3,5,7...at n=6A032137