1820
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
- 24
- Divisor Sum
- 4704
- Proper Divisor Sum (Aliquot Sum)
- 2884
- 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
- 576
- Möbius Function
- 0
- Radical
- 910
- Omega Function (Ω)
- 5
- Little Omega Function (ω)
- 4
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
- yes
- 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
- 42
- 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
- Pentagonal numbers: a(n) = n*(3*n-1)/2.at n=35A000326
- Binomial coefficient binomial(n,4) = n*(n-1)*(n-2)*(n-3)/24.at n=16A000332
- Expansion of Product (1 - x^k)^8 in powers of x.at n=34A000731
- Number of compositions of n into 5 ordered relatively prime parts.at n=12A000743
- Expansion of g.f. (1 + x + 2*x^2)/((1 - x)^2*(1 - x^3)).at n=51A000969
- Fibonomial coefficients.at n=4A001656
- Take solution to Pellian equation x^2 - n*y^2 = 1 with smallest positive y and x >= 0; sequence gives a(n) = y, or 0 if n is a square. A002350 gives values of x.at n=28A002349
- Expansion of (1-4*x)^(7/2).at n=12A002423
- Central Fibonomial coefficients.at n=4A003267
- Central Fibonomial coefficients.at n=6A003268
- Number of nonequivalent dissections of an n-gon into 3 polygons by nonintersecting diagonals up to rotation.at n=25A003451
- Binomial coefficient C(2n,n-4).at n=4A004310
- a(n) = binomial(4n,n).at n=4A005810
- If n mod 2 = 0 then n*(n^2-4)/12 else n*(n^2-1)/12.at n=28A006584
- a(n)=1, a(n+1) = lcm(a(n),b(n)) / gcd(a(n),b(n)), where {b(n)} = {fibonacci(n)}.at n=8A008341
- Expansion of (1-x^13) / (1-x)^13.at n=4A008495
- 11-dimensional centered tetrahedral numbers.at n=4A008505
- Dates of accession of the Georges to the English throne.at n=3A008744
- "Pascal sweep" for k=9: draw a horizontal line through the 1 at C(k,0) in Pascal's triangle; rotate this line and record the sum of the numbers on it (excluding the initial 1).at n=38A009540
- Coordination sequence T2 for Zeolite Code -PAR.at n=30A009856