What are the divisors of 4393?

1, 23, 191, 4393

There is a total of 4 positive divisors.
The sum of these divisors is 4608.
The arithmetic mean is 1152.

4 odd divisors

1, 23, 191, 4393

How to compute the divisors of 4393?

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 4393 by each of the numbers from 1 to 4393 to determine which ones have a remainder equal to 0.

$Remainder = N - (M \times ⌊ \frac{N}{M} ⌋)$

(where $⌊ \frac{N}{M} ⌋$ is the integer part of the quotient)

4393 / 1 = 4393 (the remainder is 0, so 1 is a divisor of 4393)
4393 / 2 = 2196.5 (the remainder is 1, so 2 is not a divisor of 4393)
4393 / 3 = 1464.3333333333 (the remainder is 1, so 3 is not a divisor of 4393)
...
4393 / 4392 = 1.0002276867031 (the remainder is 1, so 4392 is not a divisor of 4393)
4393 / 4393 = 1 (the remainder is 0, so 4393 is a divisor of 4393)

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 4393 (i.e. 66.279710319222). Indeed, if a number N has a divisor D greater than its square root, then there is necessarily a smaller divisor d such that:

$D \times d = N$

(thus, if $\frac{N}{D} = d$ , then $\frac{N}{d} = D$ )

4393 / 1 = 4393 (the remainder is 0, so 1 and 4393 are divisors of 4393)
4393 / 2 = 2196.5 (the remainder is 1, so 2 is not a divisor of 4393)
4393 / 3 = 1464.3333333333 (the remainder is 1, so 3 is not a divisor of 4393)
...
4393 / 65 = 67.584615384615 (the remainder is 38, so 65 is not a divisor of 4393)
4393 / 66 = 66.560606060606 (the remainder is 37, so 66 is not a divisor of 4393)