9480
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 21
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 32
- Divisor Sum
- 28800
- Proper Divisor Sum (Aliquot Sum)
- 19320
- 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
- 2496
- Möbius Function
- 0
- Radical
- 2370
- Omega Function (Ω)
- 6
- 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
- no
- Narcissistic Number
- no
- Collatz Steps
- 153
- 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
- Expansion of a modular function for Gamma_0(21).at n=20A002511
- s(1)t(n) + s(2)t(n-1) + ... + s(k)t(n+1-k), where k = [ (n+1)/2 ], s = A000201 (lower Wythoff sequence), t = A001950 (upper Wythoff sequence).at n=28A024686
- Number of compositions (ordered partitions) of n into distinct odd parts.at n=48A032021
- Number of partitions of n into parts not of the form 21k, 21k+10 or 21k-10. Also number of partitions with at most 9 parts of size 1 and differences between parts at distance 9 are greater than 1.at n=34A035988
- Number of nonempty subsets of {1,2,...,n} in which exactly 1/4 of the elements are <= n/2.at n=18A047163
- Number of nonempty subsets of {1,2,...,n} in which exactly 1/4 of the elements are <= (n-1)/2.at n=18A047174
- a(n) = a(1) + a(2) + ... + a(n-1) + a(m) for n >= 4, where m = 2^(p+1) + 2 - n and p is the unique integer such that 2^p < n - 1 <= 2^(p+1), starting with a(1) = 1, a(2) = 3, and a(3) = 1.at n=13A049965
- E.g.f. (1+x-x^2)/((1-x)(1-2x)).at n=5A052617
- E.g.f. (1-x)/(1-2x-3x^2+3x^3).at n=5A052664
- Numbers k such that sigma(x) = k has exactly 6 solutions.at n=41A060662
- Least k such that gcd( p(k), q(k) ) is n, where p() is the unrestricted partition function (A000041) and q is the distinct partition function (A000009).at n=36A060743
- Consider the sequence b(k) such that b(k) and sigma(b(k)) end with the same digit in base 10. Sequence gives values of b(k) such that b(k)/k = 10.at n=12A065255
- Expansion of (1-x)^(-1)/(1+2*x-x^2+2*x^3).at n=10A077923
- a(n) = prime(n) + prime(n^2).at n=33A092504
- 3 times hexagonal numbers: a(n) = 3*n*(2*n-1).at n=40A094159
- Numbers k such that the k-th and (k+1)-th primes have the same sum of squares of digits.at n=41A109182
- Generalized Mancala solitaire (A002491); to get n-th term, start with n and successively round up to next 11 multiples of n-1, n-2, ..., 1, for n>=1.at n=42A113748
- Start with 1 and repeatedly reverse the digits and add 74 to get the next term.at n=10A118225
- Numbers k such that k and k^2 use only the digits 0, 4, 7, 8 and 9.at n=19A136959
- Positive numbers n such that 2*120*n/(120+n) are integers.at n=37A162829