8805
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
- 8
- Divisor Sum
- 14112
- Proper Divisor Sum (Aliquot Sum)
- 5307
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Highly Composite
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 4688
- Möbius Function
- -1
- Radical
- 8805
- Omega Function (Ω)
- 3
- 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
- no
- Narcissistic Number
- no
- Collatz Steps
- 140
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- Squarefree Number
- yes
- 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
- no
- Odd
- yes
Appears in sequences
- Number of ordered triples of integers from [ 1..n ] with no global factor.at n=38A015631
- Least k such that gcd(prime(k)+1, prime(k+1)+1) = 2n.at n=22A067603
- Interprimes which are of the form s*prime, s=15.at n=32A075290
- Number of cycles in range [A014137(n-1)..A014138(n-1)] of permutation A127388.at n=10A127386
- Numbers k such that k and k^2 use only the digits 0, 2, 5, 7 and 8.at n=17A136916
- Starts with 2; has two properties: concatenation of its digits is same string as concatenation of digits of its first differences and sequence and first differences have no term in common. When there is a choice in choosing the next term in the first differences, choose the smallest number not yet present in either the sequence or its first differences.at n=45A139334
- Number of perfect matchings (or domino tilings) in K_6 X P_n.at n=2A145409
- a(n) = 9*n^2 - 13*n + 5.at n=31A214675
- G.f.: A(x,y) = Sum_{n>=0} n! * x^n*y^n * Product_{k=1..n} (1 + k*x) / (1 + k*x*y + k^2*x^2*y).at n=52A221971
- Numbers k such that sigma(tau(phi(k))) = phi(tau(sigma(k))).at n=40A226118
- Number of partitions of n where the frequencies alternate in parity.at n=50A242984
- Number of length n+5 0..4 arrays with every six consecutive terms having two times the sum of some two elements equal to the sum of the remaining four.at n=1A249081
- T(n,k) = Number of length n+5 0..k arrays with every six consecutive terms having two times the sum of some two elements equal to the sum of the remaining four.at n=11A249085
- Number of length 2+5 0..n arrays with every six consecutive terms having two times the sum of some two elements equal to the sum of the remaining four.at n=3A249087
- Numbers that are divisible by the product of their factorial base digits (A208575).at n=34A286590
- Number of non-isomorphic knapsack multiset partitions of weight n.at n=9A321143
- Where the zeros in A123066 occur.at n=9A321962
- Number of intersection points when every pair of vertices of a row of n adjacent congruent rectangles are joined by an infinite line.at n=13A347750
- Position of second appearance of 2n in the sequence of prime gaps A001223; if 2n does not appear at least twice, a(n) = -1.at n=22A356221
- a(n) = Sum_{k=1..n} (-1)^(k-1) * binomial(floor(n/k)+2,3).at n=37A366395