13321
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 10
- Digital Root
- 1
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 16704
- Proper Divisor Sum (Aliquot Sum)
- 3383
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 10320
- Möbius Function
- -1
- Radical
- 13321
- Omega Function (Ω)
- 3
- 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
- 169
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- 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
- Centered 20-gonal (or icosagonal) numbers.at n=36A069133
- Factorial expansion of A071156.at n=34A071158
- Smallest squarefree integer k such that Q(sqrt(k)) has class number n.at n=25A081363
- Smallest d such that real quadratic field with discriminant d has class number n.at n=25A081364
- List of molecules in Hintze-Adami artificial chemistry (see comments for definition).at n=14A101145
- Sequence representing valid nontrivial 1-dimensional Hashi (a.k.a. Bridges or Hashiwokakero) puzzle orientations.at n=33A143964
- Numbers k such that k![7]-1 is prime (where k![7] = A114799(k) = septuple factorial).at n=55A156167
- a(n) = 36*n^2 - 55*n + 21.at n=19A157262
- Run length of the n-th run of Fibonacci composites.at n=28A182600
- Number of length n+3 0..2 arrays with some disjoint pairs in every consecutive four terms having the same sum.at n=18A247527
- Zeroless numbers n with digits d_1, d_2, ... d_k such that d_1^3 + ... + d_k^3 is a cube.at n=44A254960
- The broken eggs problem.at n=31A256101
- Expansion of Product_{k>=1} 1/(1 - x^(2*k+3))^k.at n=51A263352
- Irregular triangle read by rows: T(n,k) = number of signed unichromosonal genomes with n genes at 4-break distance k from a fixed genome, 0 <= k <= floor((n+1)/3).at n=34A264617
- Number of irreducible normal polynomials of degree n over GF(2) that are not primitive.at n=19A272033
- p-INVERT of (1,1,0,0,0,0,...), where p(S) = (1 - S)(1 - 2 S).at n=8A291393
- Integers k such that for all m>k, d(m)/m < d(k)/k where d(j) = Min_{p & q odd primes, 2*j = p+q, p <= q} (q-p)/2.at n=18A335297
- Centered pentachoral numbers.at n=8A365205
- The reversing binary representation of the sum of the divisors of the n-th odd square: a(n) = A065621(A379223(n)).at n=35A379224
- a(n) is the least number k whose digit sums are 2*n-1, 2*n and 2*n+1 in bases 2*n-1, 2*n and 2*n+1 respectively.at n=3A379896