6520
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 13
- Digital Root
- 4
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 16
- Divisor Sum
- 14760
- Proper Divisor Sum (Aliquot Sum)
- 8240
- 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
- 2592
- Möbius Function
- 0
- Radical
- 1630
- 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
- no
- 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
- a(n) = dot_product(n,n-1,...2,1)*(5,6,...,n,1,2,3,4).at n=25A026060
- Second 10-gonal (or decagonal) numbers: n*(4*n+3).at n=40A033954
- Trajectory of 3 under map n->41n+1 if n odd, n->n/2 if n even.at n=8A037118
- Reversion of sequence of involutions (A000085).at n=8A050397
- Numbers n such that 279*2^n-1 is prime.at n=18A050898
- Sum of the quadratic residues of prime(n).at n=37A076409
- Shadow of sqrt(2).at n=35A110557
- Numbers m with even length such that phi(m)=phi(d_1^d_2*d_3^d_4*...* d_(k-1)^d_k) where d_1 d_2 ... d_k is the decimal expansion of m.at n=3A112010
- Numbers m with even length such that phi(m)=phi(d_1^d_2)*phi(d_3^d_4) *...*phi(d_(k-1)^d_k) where d_1 d_2 ... d_k is the decimal expansion of m.at n=3A112011
- Non-cubefree numbers k such that 2k+1 is also non-cubefree (A046099).at n=46A115170
- Numbers k such that k and k+5 are 5-almost primes.at n=22A124942
- Number of equivalence classes of normalized Hadamard matrices of order 4n with respect to permutations of rows and columns.at n=4A147774
- Integers n such that (25*10^n)+1 is prime.at n=9A171612
- Triangle T(n,k) = 1 - A176304(k) - A176304(n-k) + A176304(n), read by rows.at n=31A176306
- Triangle T(n,k) = 1 - A176304(k) - A176304(n-k) + A176304(n), read by rows.at n=32A176306
- T(n,k)=Number of n-step one space leftwards or up, two space rightwards or down asymmetric rook's tours on a kXk board summed over all starting positions.at n=60A187296
- Number of 6-step one space leftwards or up, two space rightwards or down asymmetric rook's tours on an n X n board summed over all starting positions.at n=5A187301
- a(n) = 1 + (n-1) + (n-2)*[(n-3)/2] + (n-3)*[(n-4)/2]*[(n-5)/3] + (n-4)*[(n-5)/2]*[(n-6)/3]*[(n-7)/4] +... where [x] = floor(x), with summation extending over the initial [n/2+1] products only.at n=20A207644
- Number of n X n 0..3 arrays with new values 0..3 introduced in row major order and no element equal to more than one of its immediate leftward or upward or right-upward antidiagonal neighbors.at n=2A208865
- Number of n X 3 0..3 arrays with new values 0..3 introduced in row major order and no element equal to more than one of its immediate leftward or upward or right-upward antidiagonal neighbors.at n=2A208867