6868
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
- 12
- Divisor Sum
- 12852
- Proper Divisor Sum (Aliquot Sum)
- 5984
- 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
- 3200
- Möbius Function
- 0
- Radical
- 3434
- Omega Function (Ω)
- 4
- 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
- 106
- 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
- G.f.: Product_{k>=1} (1 + x^(2*k - 1)) / (1 - x^(2*k)).at n=42A006950
- a(n) = C(n+2, 2) + C(n+2, 3) + C(n+2, 4) + C(n+2, 5).at n=14A027660
- Four times pentagonal numbers: a(n) = 2*n*(3*n-1).at n=34A033579
- a(n) = T(2n-1,n), array T given by A048201.at n=41A048208
- Numbers k such that sigma(k) - k = k - pi(k) - 1 where pi(k) is A000720.at n=8A048884
- Numbers k such that k | sigma_5(k).at n=38A055709
- Numbers k such that 2*5^k - 3 is prime.at n=18A057915
- a(n) = A077347(n)^(1/2).at n=46A077349
- Number of walks of length n between two nodes at distance 2 in the cycle graph C_9.at n=15A095367
- G.f.: Product_{k>0} (1-x^(2k-1))/(1-x^(2k)).at n=42A106507
- Partial sums of A032598.at n=11A129330
- Triangle read by rows: T(n,k) is the number of paths in the first quadrant from (0,0) to (n,0), consisting of steps U=(1,1), D=(1,-1), h=(1,0) and H=(2,0), having k doublerises (i.e., UU's) (0 <= k <= floor(n/2) - 1 for n >= 2).at n=28A132279
- Number of n X n binary arrays symmetric under 180 degree rotation with all ones connected only in two by two blocks.at n=9A145864
- Number of walks within N^2 (the first quadrant of Z^2) starting at (0,0) and consisting of n steps taken from {(-1, -1), (-1, 1), (0, 1), (1, -1)}.at n=10A151258
- Indices of 4's in A090822.at n=30A157107
- Number of slanted nX6 (i=1..n)X(j=i..6+i-1) 1..4 arrays with all 1s connected, all 2s connected, all 3s connected, all 4s connected, 1 in the upper left corner, 2 in the upper right corner, 3 in the lower left corner, and 4 in the lower right corner.at n=1A165375
- Number of slanted 3 X n (i=1..3) X (j=i..n+i-1) 1..4 arrays with all 1s connected, all 2s connected, all 3s connected, all 4s connected, 1 in the upper left corner, 2 in the upper right corner, 3 in the lower left corner, and 4 in the lower right corner.at n=4A165386
- Multiples of 17 whose reversal + 1 is also a multiple of 17.at n=21A166391
- Number of distinct solutions of sum{i=1..2}(x(2i-1)*x(2i)) = 0 (mod n), with x() in 0..n-1.at n=36A180794
- a(n+1) = a(n) + floor(a(n)/5) with a(0)=5.at n=42A182306