C/C++ :: Find Sum Of Prime Factors Of User Input Integer

As an assignment for school , I've to write a program to find the sum prime factors of a user input integer.

E.g. 20 = 2 x 2 x 5 , Sum = 2 + 2 + 5 = 9
E.g. 10 = 2 x 5 , Sum = 2 + 5 = 7

My method for finding the result is as follows :

- Divide the number by increasing values if int i , starting from i=2.

- Once I get a value of i that can divide the number without giving me a remainder , I add this value of i to int sum and divide the number by i.

- I will repeat this process until the user input value is equal to 1.

My code is as shown:

#include<stdio.h>
int primecheck(int n); // Function to check if i is prime
int primesum(int n); // Function to sum the values of i that are prime
int main(void) {
int n;
int sum;
printf("Enter a number (> 1): "); //Prompting and scanning user input ,n
scanf("%d",&n);
sum = primesum(n);

[Code] .....

But for some reason I keep getting an incorrect result, it's as if it is missing out the last factor for each case.

Eg. 20 = 2 x 2 x 5 , the result I get is 4 , which is 2+2
Eg. 40 = 2 x 2 x 2 x 5 , the result I get is 6 , which is 2+2+2;

I've looked through my code numerous times.