What are the divisors of 1607?

1, 1607

There is a total of 2 positive divisors.
The sum of these divisors is 1608.
The arithmetic mean is 804.

2 odd divisors

1, 1607

How to compute the divisors of 1607?

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 1607 by each of the numbers from 1 to 1607 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)

1607 / 1 = 1607 (the remainder is 0, so 1 is a divisor of 1607)
1607 / 2 = 803.5 (the remainder is 1, so 2 is not a divisor of 1607)
1607 / 3 = 535.66666666667 (the remainder is 2, so 3 is not a divisor of 1607)
...
1607 / 1606 = 1.0006226650062 (the remainder is 1, so 1606 is not a divisor of 1607)
1607 / 1607 = 1 (the remainder is 0, so 1607 is a divisor of 1607)

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 1607 (i.e. 40.087404505655). 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 $\frac{N}{d} = D$ )

1607 / 1 = 1607 (the remainder is 0, so 1 and 1607 are divisors of 1607)
1607 / 2 = 803.5 (the remainder is 1, so 2 is not a divisor of 1607)
1607 / 3 = 535.66666666667 (the remainder is 2, so 3 is not a divisor of 1607)
...
1607 / 39 = 41.205128205128 (the remainder is 8, so 39 is not a divisor of 1607)
1607 / 40 = 40.175 (the remainder is 7, so 40 is not a divisor of 1607)