13725
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 18
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 18
- Divisor Sum
- 24986
- Proper Divisor Sum (Aliquot Sum)
- 11261
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 7200
- Möbius Function
- 0
- Radical
- 915
- 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
- 120
- 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
- no
- Odd
- yes
Appears in sequences
- Expansion of (1+2*x+3*x^2)/((1-x)^3*(1-x^2)).at n=29A055232
- Starting positions of strings of three 2's in the decimal expansion of Pi.at n=20A083606
- G.f.: (x+4*x^3+x^5)/((1-x)^2*(1-x^2)^2*(1-x^3)).at n=27A083707
- First n numbers in binary representation concatenated in reverse order.at n=5A098780
- Terms of A110566 grouped.at n=60A112811
- Numbers k for which nontrivial positive magic squares of exactly 9 different orders with magic sum k exist. For a definition of nontrivial positive magic squares, see A125005.at n=26A125016
- a(n) = 4*A000984(n) - 3.at n=7A134770
- A134770 interleaved with threes.at n=14A134771
- a(n) = 61*n^2.at n=15A174333
- Unchanging value maps: number of nX4 binary arrays indicating the locations of corresponding elements unequal to no horizontal, antidiagonal or vertical neighbor in a random 0..1 nX4 array.at n=5A219152
- Unchanging value maps: number of n X 6 binary arrays indicating the locations of corresponding elements unequal to no horizontal, antidiagonal or vertical neighbor in a random 0..1 n X 6 array.at n=3A219154
- T(n,k)=Unchanging value maps: number of nXk binary arrays indicating the locations of corresponding elements unequal to no horizontal, antidiagonal or vertical neighbor in a random 0..1 nXk array.at n=39A219156
- T(n,k)=Unchanging value maps: number of nXk binary arrays indicating the locations of corresponding elements unequal to no horizontal, antidiagonal or vertical neighbor in a random 0..1 nXk array.at n=41A219156
- T(n,k)=Number of (n+1)X(k+1) arrays of permutations of 0..(n+1)*(k+1)-1 with each element having index change +-(.,.) 0,0 0,2 or 1,2.at n=28A264131
- Number of (1+1)X(n+1) arrays of permutations of 0..n*2+1 with each element having index change +-(.,.) 0,0 0,2 or 1,2.at n=7A264132
- a(n) = f(n,n) where f(m,n) = max(m,n) if m < 2 or n < 2; f(m,n) = f(m-1,n-1) + f(m-1,n-2) + f(m-2,n-1) otherwise. Diagonal of A342859.at n=12A342600
- Odd numbers k such that sigma(k) + sigma(k+2) > 2*sigma(k+1); odd terms in A053228.at n=31A358395
- Primitive terms of A359563: terms of A359563 with no proper divisor in A359563.at n=29A359564
- Numbers k > 2 such that all positive values of k - 2^(2^m) are prime, with integer m >= 0.at n=51A370523
- Terms k of A228058 for which A048146(k)+A162296(k) >= 2*k, where A048146 is the sum of non-unitary divisors, and A162296 is the sum of divisors that have a square factor.at n=19A389219