13089
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 21
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 17456
- Proper Divisor Sum (Aliquot Sum)
- 4367
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 8724
- Möbius Function
- 1
- Radical
- 13089
- 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
- 138
- 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
- a(n) = T(n,n), T given by A026568. Also a(n) = number of integer strings s(0),...,s(n) counted by T, such that s(n)=0.at n=12A026569
- a(n) = Sum_{k=0..n} binomial(2*k,k)*binomial(2*n-k,k).at n=6A027277
- Numbers k such that the continued fraction for sqrt(k) has even period and if the last term of the periodic part is deleted the central term is 76.at n=24A031574
- a(n) = A007290(n+2) - 1 = 2*C(n+2,3) - 1.at n=33A108766
- Number of n X n symmetric positive definite matrices with 2's on the main diagonal and -1, 0, or 1 elsewhere.at n=4A114601
- Number of n-plaquette surfaces embedded in a 3D simple cubic lattice.at n=4A118331
- Number of partitions p of n such that mean(p) > multiplicity(min(p)).at n=38A240206
- Number of (n+1) X (3+1) 0..2 arrays with nondecreasing x(i,j)-x(i,j-1) in the i direction and nondecreasing x(i,j)+x(i-1,j) in the j direction.at n=4A250750
- T(n,k)=Number of (n+1)X(k+1) 0..2 arrays with nondecreasing x(i,j)-x(i,j-1) in the i direction and nondecreasing x(i,j)+x(i-1,j) in the j direction.at n=25A250755
- Number of (5+1) X (n+1) 0..2 arrays with nondecreasing x(i,j)-x(i,j-1) in the i direction and nondecreasing x(i,j)+x(i-1,j) in the j direction.at n=2A250760
- Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 201", based on the 5-celled von Neumann neighborhood.at n=27A270722
- Numbers n such that the decimal number concat(6,n) is a square.at n=27A273361
- Odd numbers k such that phi(k) and cototient(k) have the same prime signature.at n=16A280927
- Sum of the squarefree parts of the partitions of n into 4 parts.at n=41A309479
- Number of partitions of 2n into exactly n nonzero decimal palindromes.at n=40A319454
- Number of integer partitions of n with sortable prime factors.at n=36A326333
- a(n) is the smallest k such that k!'s prime(n)-smooth part is less than its prime(n+1)-rough part.at n=27A360316
- Number of polycubes with 8*n cells, full symmetry, and the rotation point of the symmetries at the common corner of 8 cells (that may or may not be part of the polycube).at n=31A377335