13105
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
- 1
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 15732
- Proper Divisor Sum (Aliquot Sum)
- 2627
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 10480
- Möbius Function
- 1
- Radical
- 13105
- 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
- Number of series-reduced planted compound windmills with n leaves of 2 colors where any 2 submills extending from the same node are different.at n=9A032163
- Numbers whose set of base-16 digits is {1,3}.at n=28A032923
- Decimal part of n-th root of a(n) starts with digit 2.at n=50A034079
- Number of primes of the form 7k+3 less than 10^n.at n=5A091122
- Number of primes of the form 7k+5 less than 10^n.at n=5A091124
- Numbers such that the sum of the factorials of the digits of the cube is a square.at n=36A126076
- Number of slanted 2 X n (i=1..2) X (j=i..n+i-1) 1..4 arrays with all 1s connected, all 2s connected, all 3s connected, all 4s connected, 1 in the upper left corner, 2 in the upper right corner, 3 in the lower left corner, 4 in the lower right corner, and with no element having more than 3 neighbors with the same value.at n=13A165394
- a(n) = 2*n*(n+1)*(n+2)/3 + (-1)^n.at n=26A179783
- Number of ordered triples (w,x,y) with all terms in {1,...,n} and w^2<=x^2+y^2.at n=26A211634
- Beach-Williams Pell numbers of type pq (p,q primes).at n=11A212078
- The hyper-Wiener index of the straight pentachain of n pentagonal rings (see Fig. 2.1 in the A. A. Ali et al. reference).at n=9A224460
- Numbers such that Liouville's function (A002819) and the little omega analog to Liouville's function (A174863) are equal.at n=37A224987
- Number of second differences of arrays of length 4 of numbers in 0..n.at n=35A228219
- Indices of heptagonal numbers (A000566) which are also centered square numbers (A001844).at n=3A254228
- Number of (n+2) X (1+2) 0..1 arrays with no 3 x 3 subblock diagonal sum 1 and no antidiagonal sum 1 and no row sum 1 and no column sum 1.at n=7A255094
- T(n,k) = Number of (n+2) X (k+2) 0..1 arrays with no 3 X 3 subblock diagonal sum 1 and no antidiagonal sum 1 and no row sum 1 and no column sum 1.at n=28A255101
- T(n,k) = Number of (n+2) X (k+2) 0..1 arrays with no 3 X 3 subblock diagonal sum 1 and no antidiagonal sum 1 and no row sum 1 and no column sum 1.at n=35A255101
- Main diagonal of Unlucky array: a(n) = A255543(n,n).at n=21A255549
- Indices of zeros in A268819.at n=57A269157
- a(n) = 10*n^2 + 4*n + 1.at n=36A272039