8280
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 18
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 48
- Divisor Sum
- 28080
- Proper Divisor Sum (Aliquot Sum)
- 19800
- 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
- 2112
- 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
- 127
- 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
- Denominator in Feinler's formula for unsigned Bernoulli number |B_{2n}|.at n=11A002444
- Denominators of Cauchy numbers of first type.at n=22A006233
- Expansion of Product_{k>=1} (1 - x^k)^18.at n=7A010824
- a(n) = floor( n*(n-1)*(n-2)/11 ).at n=46A011893
- Consider all complete bipartite graphs on 2n nodes and all possible assignment of weights w(i) (for nodes i=1,...,2n); sequence gives maximal number of ways to orient the edges of the graph so that each node i has w(i) edges oriented towards it (for i=1,...,2n).at n=9A014627
- 8 times triangular numbers: a(n) = 4*n*(n+1).at n=45A033996
- Positive numbers having the same set of digits in base 8 and base 9.at n=33A037441
- Ruth-Aaron numbers (2): sum of prime divisors of n = sum of prime divisors of n+1 (both taken with multiplicity).at n=18A039752
- E.g.f.: x/(1-x)+log((1-x)/(1-2*x)).at n=6A052850
- Numbers k such that k | sigma_11(k).at n=24A055715
- Freestyle perfect numbers n = Product_{i=1,..,k} f_i^e_i where 1 < f_1 < ... < f_k, e_i > 0, such that 2n = Product_{i=1,..,k} (f_i^(e_i+1)-1)/(f_i-1).at n=36A058007
- a(0)=1, a(n) = 8*n*(2*n-1).at n=23A067239
- Numbers n such that n*tau(n)>prime(4*n) where tau(n)=A000005(n).at n=38A068352
- First differences of A069475, successive differences of (n+1)^6-n^6.at n=9A069476
- Number of connected circulant graphs on n nodes.at n=31A075545
- Numbers k such that tau(k) = sigma(sopf(k)).at n=41A075867
- Second member of Diophantine pair (m,k) that satisfies 6*(m^2 + m) = k^2 + k: a(n) = k.at n=8A077291
- Expansion of e.g.f.: (1+x)*exp(5*x)*cosh(x).at n=5A082309
- (8*5^n - 5*2^n)/3.at n=5A083585
- Local maxima of A053707 (first differences of A025475, powers of a prime but not prime).at n=41A088365