How to use whether a number is prime or not in C Language

#include <stdio.h>
#include <math.h>
int main()
{
    int i, n;
    printf("enter a number : ");
    scanf("%d", &n);
    for (i = 2; i <= sqrt(n); i++)
    {
        if (n % i == 0)
        {
            break;
        }
    }
    if (i > sqrt(n))
    {
        printf("%d is prime\n", n);
    }
    else
    {
        printf("%d is not prime\n", n);
    }
    return 0;
}