What are the divisors of 4043?

1, 13, 311, 4043

4 odd divisors

1, 13, 311, 4043

How to compute the divisors of 4043?

A number N is said to be divisible by a number M (with M non-zero) if, when we divide N by M, the remainder of the division is zero.

N mod M = 0

Brute force algorithm

We could start by using a brute-force method which would involve dividing 4043 by each of the numbers from 1 to 4043 to determine which ones have a remainder equal to 0.

Remainder = N ( M × N M )

(where N M is the integer part of the quotient)

  • 4043 / 1 = 4043 (the remainder is 0, so 1 is a divisor of 4043)
  • 4043 / 2 = 2021.5 (the remainder is 1, so 2 is not a divisor of 4043)
  • 4043 / 3 = 1347.6666666667 (the remainder is 2, so 3 is not a divisor of 4043)
  • ...
  • 4043 / 4042 = 1.0002474022761 (the remainder is 1, so 4042 is not a divisor of 4043)
  • 4043 / 4043 = 1 (the remainder is 0, so 4043 is a divisor of 4043)

Improved algorithm using square-root

However, there is another slightly better approach that reduces the number of iterations by testing only integers less than or equal to the square root of 4043 (i.e. 63.584589327918). Indeed, if a number N has a divisor D greater than its square root, then there is necessarily a smaller divisor d such that:

D × d = N

(thus, if N D = d , then N d = D )

  • 4043 / 1 = 4043 (the remainder is 0, so 1 and 4043 are divisors of 4043)
  • 4043 / 2 = 2021.5 (the remainder is 1, so 2 is not a divisor of 4043)
  • 4043 / 3 = 1347.6666666667 (the remainder is 2, so 3 is not a divisor of 4043)
  • ...
  • 4043 / 62 = 65.209677419355 (the remainder is 13, so 62 is not a divisor of 4043)
  • 4043 / 63 = 64.174603174603 (the remainder is 11, so 63 is not a divisor of 4043)