21. Write a C program to check the accepted number is prime number or not.

#include <stdio.h>
void main()
{
    int n, i, m = 0, flag = 0;

    printf("Enter the number : ");
    scanf("%d", &n);

    m = n / 2;

    for (i = 2; i <= m; i++)
    {
        if (n % i == 0)
        {
            printf("This Number is not prime");
            flag = 1;
            break;
        }
    }

    if (flag == 0)
        printf("This Number is prime");
}