6680
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
- 1
Divisibility
- Divisor Count
- 16
- Divisor Sum
- 15120
- Proper Divisor Sum (Aliquot Sum)
- 8440
- 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
- 2656
- Möbius Function
- 0
- Radical
- 1670
- Omega Function (Ω)
- 5
- 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
- yes
- Narcissistic Number
- no
- Collatz Steps
- 137
- 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
- Number of alkyls S C_{n+4} H_{2n+4} with n carbon atoms.at n=10A000650
- Numbers k such that sigma(k) = sigma(k+8).at n=14A015876
- Number of dyslexic rooted compound windmills with n nodes where any 2 submills extending from the same node are different.at n=14A032235
- Numbers whose base-9 representation has exactly 5 runs.at n=26A043634
- Length of A001388(n).at n=29A046639
- Numbers n such that 213*2^n-1 is prime.at n=28A050858
- Local ranks of terms of A057122.at n=41A057124
- Number of essentially different ways in which the squares 1,4,9,...,n^2 can be arranged in a sequence such that all pairs of adjacent squares sum to a prime number. Rotations and reversals are counted only once.at n=15A073451
- Pair the natural numbers such that the n-th pair is (k, k+p(n)) where k is the smallest number not occurring earlier and p(n) is the n-th prime. (1, 3), (2, 5), (4, 9), (6, 13), (7, 18), (8, 21), (10, 27), (11, 30), (12, 35), (14, 43), ... This is the sequence of the product of the members of every pair.at n=30A075316
- Molien series for complete weight enumerators of Hermitian self-dual codes over GF(9) containing the all-ones vector.at n=5A092355
- Numerators of the convergents in the continued fraction expansion for twice the constant given by A100338, where the partial quotients equal A006519 (greatest power of 2 dividing n) interleaved with 2's.at n=10A100342
- Smallest number m such that A114228(m) = n.at n=41A114229
- n+phi(n)+phi(phi(n)) is a cube.at n=11A116042
- Triangle, read by rows, where the g.f. of column k, C_k(x), is defined by the recurrence: C_k(x) = [ 1 + Sum_{n>=k+1} C_n(x)*x^(n-k) ]^(k+1) for k>=0.at n=40A127126
- Central terms of triangle A127126; a(n) = A127126(2n,n).at n=4A127134
- Numbers k such that k and k^2 use only the digits 0, 2, 4, 6 and 8.at n=22A136904
- Number of planar n X n X n binary triangular grids symmetric both under 120 degree rotation and reflection with no more than 9 ones in any 5 X 5 X 5 subtriangle.at n=11A153970
- a(n) = 250*n - 70.at n=27A154361
- First differences of A160379.at n=15A163989
- n times the n-th noncomposite.at n=39A164931