13505
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 14
- Digital Root
- 5
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 16872
- Proper Divisor Sum (Aliquot Sum)
- 3367
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 10368
- Möbius Function
- -1
- Radical
- 13505
- 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
- From reversion of e.g.f. for squares.at n=5A066399
- a(n) = Sum_{i=0..n} binomial(n,i)^2*i!*4^i.at n=4A102773
- Numbers k such that the sum of the Carmichael lambda functions of the divisors is a proper divisor of k.at n=16A131492
- Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, 1), (-1, 1, -1), (0, 0, 1), (1, -1, 1), (1, 0, 0)}.at n=9A149832
- 5 times hexagonal numbers: 5*n*(2*n-1).at n=37A152745
- a(n)=sum{k=0..floor(n/2), binomial(n-k,k)*A186338(k)}.at n=11A186341
- Number of connected regular graphs with n nodes and girth at least 6.at n=37A186726
- Distinct values of A218788 in the order of appearance.at n=23A218610
- Number of partitions of n such that the number of parts having multiplicity >1 is a part and the number of distinct parts is a part.at n=42A241409
- a(n) = 4*n^3 + 5.at n=16A243762
- Numbers n such that A002496(n) mod A002496(n-1) is a perfect square.at n=34A247592
- Number of (2+2)X(n+2) 0..3 arrays with every 3X3 subblock row and diagonal sum equal to 0 3 5 6 or 7 and every 3X3 column and antidiagonal sum not equal to 0 3 5 6 or 7.at n=12A252386
- Maximally idempotent integers with three or more factors.at n=24A306812
- a(n) = n! * Sum_{k=0..n} binomial(n,k) * n^(n - k) / k!.at n=4A330260
- Sum of the areas of all r X s rectangles such that r + s = 2n, with r, s composite.at n=31A334229
- Square array T(n,k), n >= 0, k >= 0, read by antidiagonals, where T(n,k) = Sum_{j=0..n} k^j * j! * binomial(n,j)^2.at n=40A341014
- Number of ways to write n as an ordered sum of 5 nonprime numbers.at n=44A341482
- Number of integer partitions of n containing all of their own nonzero first differences.at n=43A364674
- a(n) = floor(Sum_{k=n^3..(n+1)^3} k^(1/3)).at n=16A374384