7661
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 20
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 7872
- Proper Divisor Sum (Aliquot Sum)
- 211
- 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
- 7452
- Möbius Function
- 1
- Radical
- 7661
- Omega Function (Ω)
- 2
- Little Omega Function (ω)
- 2
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
- 176
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- yes
- 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
- Representation degeneracies for boson strings.at n=33A005291
- Numbers k such that the continued fraction for sqrt(k) has period 84.at n=19A020423
- Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 40 ones.at n=39A031808
- Numbers whose base-5 representation contains exactly three 1's and three 2's.at n=17A045232
- a(1) = 9; a(n) is smallest number >= a(n-1) such that the juxtaposition a(1)a(2)...a(n) is a prime.at n=43A046259
- a(n) = (A085249(n) - 1)/6.at n=15A088349
- Maximal value of sum(p(i)p(i+1),i=1..n), where p(n+1)=p(1), as p ranges over all permutations of {1,2,...,n}.at n=27A110610
- Semiprimes which are the sum of two pentagonal numbers (A000326) in exactly two different ways.at n=41A120536
- a(n) = 2*a(n-1) - a(n-2) + 2*(prime(n+1)-prime(n)); a(1) = 2, a(2) = 3.at n=43A122263
- Isotopy classes of unordered Latin bi-trades of size n.at n=13A133176
- Numbers k such that 6*prime(k) -+ {1,5} are all prime.at n=15A174393
- Partial sums of A004207.at n=43A176718
- Positive integers of the form (30*m^2+1)/11.at n=9A179339
- Number of (n+3)X(n+3) binary arrays with every 4X4 subblock commuting with each horizontal and vertical neighbor 4X4 subblock.at n=4A188096
- Number of (n+3) X 8 binary arrays with every 4 X 4 subblock commuting with each horizontal and vertical neighbor 4 X 4 subblock.at n=4A188101
- T(n,k)=Number of (n+3)X(k+3) binary arrays with every 4X4 subblock commuting with each horizontal and vertical neighbor 4X4 subblock.at n=40A188105
- Inverse permutation to A190130.at n=3A190131
- a(n) = 25*n^2 + 15*n + 1021.at n=16A214732
- Triangle T(n, k) = Number of non-equivalent (mod D_3) ways to arrange k indistinguishable points on a triangular grid of side n so that no three points are collinear. Triangle read by rows.at n=42A234350
- Number of non-equivalent (mod D_3) ways to arrange 4 indistinguishable points on a triangular grid of side n so that no three points are collinear.at n=5A234352