6688
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 28
- Digital Root
- 1
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 24
- Divisor Sum
- 15120
- Proper Divisor Sum (Aliquot Sum)
- 8432
- 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
- 2880
- Möbius Function
- 0
- Radical
- 418
- Omega Function (Ω)
- 7
- 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
- 44
- 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
- a(0) = 1, a(1) = 0, a(2) = -1; for n >= 3, a(n) = - a(n-2) + Sum_{ primes p with 3 <= p <= n} a(n-p).at n=64A002121
- a(n) = 2*(a(n-1) + a(n-2)), a(0) = 0, a(1) = 1.at n=10A002605
- Number of ordered quadruples of integers from [ 1..n ] with no global factor.at n=18A015634
- Longest edge a of smallest (measured by the longest edge) primitive Euler bricks (a, b, c, sqrt(a^2 + b^2), sqrt(b^2 + c^2), sqrt(a^2 + c^2) are integers).at n=14A031173
- Numbers n such that there are equal numbers of 0's and 1's in first n digits of binary representation of Pi.at n=35A039624
- Numbers whose base-9 representation has exactly 5 runs.at n=33A043634
- Numbers whose base-4 representation contains exactly three 0's and three 2's.at n=28A045055
- Numbers whose base-5 representation contains exactly three 2's and two 3's.at n=23A045276
- a(n) = Sum_{i=0..n} T(i,n-i), array T as in A049747.at n=27A049748
- Molien series for group H_{1,3}^{8} of order 2304.at n=28A051531
- Smallest multiple of n with no isolated digits.at n=31A052191
- Number of directed EG-convex polyominoes on the honeycomb lattice with given semiperimeter.at n=14A053151
- Number of permutations (p_1, ..., p_n) of {1,...,n} that are "balanced" in the sense that the sum of k*p_k equals the sum of (n+1-k)*p_k; equivalently, the expected value of k*p_k is (expected value of k) times (expected value of p_k), assuming the uniform distribution.at n=9A056876
- Convolution triangle of A002605(n) (generalized (2,2)-Fibonacci), n>=0.at n=45A073387
- Fifth subdiagonal in array of n-gonal numbers A081422.at n=18A081436
- Main diagonal of array A082224.at n=41A082227
- Map from binary trees of size n to the set of corresponding trivalent plane trees (tpt) represented as size 2n+1 general trees.at n=22A083930
- Number of solid partitions non-symmetric under L^2 (L= 'time-lapse' symmetry operation) on solid partitions.at n=11A096581
- Array read by antidiagonals, generated by the matrix M = [1,1,1;1,N,1;1,1,1].at n=54A103280
- Non-cubefree numbers k such that 2k+1 is also non-cubefree (A046099).at n=48A115170