12420
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 9
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 48
- Divisor Sum
- 40320
- Proper Divisor Sum (Aliquot Sum)
- 27900
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 3168
- Möbius Function
- 0
- Radical
- 690
- Omega Function (Ω)
- 7
- 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
- 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
- 156
- 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
- MacMahon's generalized sum of divisors function.at n=44A002127
- Octagonal pyramidal numbers: a(n) = n*(n+1)*(2*n-1)/2.at n=22A002414
- Infinitary sociable numbers (smallest member of cycle).at n=3A004607
- Initial pile sizes which guarantee a win for player 2 in a certain variant of Nim.at n=41A016741
- Numbers k such that sigma(x) = k has exactly 8 solutions.at n=28A060664
- Numbers k such that sigma(k) = 2*usigma(k).at n=36A063880
- Values of m such that N=(am+1)(bm+1)(cm+1) is a 3-Carmichael number (A087788), where a,b,c = 1,2,13.at n=7A064243
- Values of m such that N=(am+1)(bm+1)(cm+1) is a 3-Carmichael number (A087788), where a,b,c = 1,2,49.at n=2A064261
- a(n) = (n+1)*(2*n+1)*(4*n+1).at n=11A079588
- Molien series for action of SL(3,C) on ternary forms of degree 4.at n=29A083024
- Least k such that k * M(n) * M(n+1) + 1 is prime where M(n) = A000668(n).at n=16A098917
- Structured icosidodecahedral numbers.at n=11A100147
- E.g.f.: 5x/(-1+1/(-1+1/(-1+1/(-1+log(1+5x))))) = -5x[3-2log(1+5x)]/[5-3log(1+5x)].at n=6A109591
- a(n) = binomial(n,3) - binomial(floor(n/2),3) - binomial(ceiling(n/2),3).at n=47A111384
- Self-convolution of A088716, where a(n) = 2*A088716(n+1)/(n+2) for n>=0.at n=6A112916
- a(1) =a(2) =1. a(n+1) = (sum{1<=k<=n/2} a(k)) * (sum{n/2<j<=n} a(j)).at n=9A113844
- Number of permutations of length n which avoid the patterns 123 and 4312.at n=22A116699
- Expansion of (1 + x + x^2) / (1 - 3*x - 3*x^2).at n=7A123620
- 12 times hexagonal numbers: 12*n*(2*n-1).at n=23A143698
- Number of reduced words of length n in Coxeter group on 24 generators S_i with relations (S_i)^2 = (S_i S_j)^3 = I.at n=3A162810