13445
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 17
- Digital Root
- 8
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 16140
- Proper Divisor Sum (Aliquot Sum)
- 2695
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 10752
- Möbius Function
- 1
- Radical
- 13445
- 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
- 45
- 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
- a(n) = 8*n^2 - 3.at n=40A108928
- Positive numbers y such that y^2 is of the form x^2+(x+937)^2 with integer x.at n=6A160209
- a(n) = Sum of all numbers of divisors of all numbers < (n+1)^2.at n=40A168011
- Numbers n such that 6n and 12n are both the average of twin prime pairs.at n=25A177680
- Moebius inversion of a sequence related to powers of 2.at n=19A178738
- E.g.f. A(x) satisfies A(x) = x * (1 + A(x)) * exp( A(x) * (1 + A(x)) ).at n=4A178920
- Positive integers of the form (6*m^2 + 1)/11.at n=28A179337
- Coefficient of x in the reduction by x^2->x+1 of the polynomial p(n,x) defined below in Comments.at n=15A192756
- Minimum value unattainable as the sum of 2 attained values of a*b*c with a,b,c 0..n integers.at n=22A225264
- Minimum value unattainable as the sum of 2 attained values of a*b*c with a,b,c 0..n integers.at n=23A225264
- Numbers n such that 6*14^n-1 is prime.at n=5A273518
- Number of maximal sum-free and product-free subsets of {1..n}.at n=35A326497
- Odd numbers k such that phi(k) = phi(k+2), where phi is the Euler totient function (A000010).at n=7A333741