13287
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
- 4
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 18304
- Proper Divisor Sum (Aliquot Sum)
- 5017
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 8568
- Möbius Function
- -1
- Radical
- 13287
- 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
- 76
- 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 octahedral numbers (crystal ball sequence for cubic lattice).at n=21A001845
- a(n) = C(n,1) + C(n,2) + C(n,3), or n*(n^2 + 5)/6.at n=43A004006
- 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=32A031574
- a(n) = floor((1/2 * (sqrt(2) + 1 + sqrt(2*sqrt(2) - 1)))^n ).at n=15A050243
- Number of 3 X 3 matrices, with elements from {0,...,n}, having the property that the middle element of each of the eight 3-element horizontal, vertical and diagonal lines equals the average of the two end elements.at n=42A059329
- a(n) = smallest m >= 1 such that Sum_{k=1..m} log(k)/k >= n.at n=45A092753
- Number of partitions of triangular numbers n*(n+1)/2 into (n-2) distinct parts for n>=3.at n=15A104384
- Numbers k such that the k-th triangular number contains only digits {2,7,8}.at n=9A119179
- Sum of all numbers from n to n-th prime.at n=38A161624
- Partial sums of A080715.at n=31A268403
- Expansion of Product_{k>=1} (1 + x^(2*k-1))^(k*(k-1)/2).at n=31A294777
- Number of square plane partitions of n with distinct row sums and distinct column sums.at n=34A306320
- Number of unlabeled rooted trees with n nodes where all terminal rooted subtrees are either constant or strict.at n=13A316522
- Total sum of the parts in all partitions counted by A339479(n).at n=7A343801
- a(n) = Sum_{j=1..n} Sum_{i=1..n} (j mod i).at n=38A367379
- Number of integers of the form (x^4 + y^4) mod 3^n; a(n) = A289559(3^n).at n=9A367484