1220
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
- 12
- Divisor Sum
- 2604
- Proper Divisor Sum (Aliquot Sum)
- 1384
- 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
- 480
- Möbius Function
- 0
- Radical
- 610
- 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
- yes
- Narcissistic Number
- no
- Collatz Steps
- 39
- 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
- Number of positive integers <= 2^n of form x^2 + 12 y^2.at n=13A000021
- a(n) = sigma_2(n): sum of squares of divisors of n.at n=32A001157
- Numbers k such that the k-th tetrahedral number is the sum of 2 tetrahedral numbers.at n=35A002311
- a(n) = ceiling(n*phi^7), where phi is the golden ratio, A001622.at n=42A004962
- Number of binary vectors of length n containing no singletons.at n=16A006355
- Triangular numbers plus quarter squares: n*(n+1)/2 + floor(n^2/4) (i.e., A000217(n) + A002620(n)).at n=40A006578
- Integers written in factorial base.at n=40A007623
- Coordination sequence T1 for Zeolite Code AEL.at n=23A008004
- Coordination sequence T7 for Zeolite Code MTW.at n=23A008202
- Coordination sequence T3 for Zeolite Code SGT.at n=22A008231
- Expansion of (1+x)/((1-x)*(1-x^2)*(1-x^3)*(1-x^4)).at n=40A008762
- Expansion of e.g.f. cos(log(1+x)*exp(x)).at n=8A009030
- a(n) = 10*a(n-1) + 11*a(n-2).at n=4A015592
- Numbers n such that phi(n) * sigma(n) + 4 is a perfect square.at n=28A015727
- Numerator of sum of -2nd powers of divisors of n.at n=32A017667
- Squares on infinite chessboard at n moves from center using a {2,3} fairy knight.at n=19A018839
- The sequence M(n) in A022905.at n=16A022908
- Self-convolution of natural numbers >= 3.at n=14A023551
- a(n) = s(1)*t(n) + s(2)*t(n-1) + ... + s(k)*t(n+1-k), where k = floor((n+1)/2), s = A023531, t = (F(2), F(3), ...).at n=15A024322
- Position of n^2 + (n+1)^2 in A000404 (sums of 2 nonzero squares).at n=45A024519