C program to find whether the given number is prime number or not

#include< stdio.h >
#include< conio.h >
void main()
{
          int i=2,num;
         clrscr();
          printf("Enter a number:");
         scanf("%d",&num);
         while(num%i!=0)
         {
                      i++;
          }
           if(num==i)
          {
                      printf("The number %d is a prime Number",num);
          }
          else
          {
                    printf("The number %d is not a prime number",num);
          }
          getch();
}

OUTPUT :

Enter a number :13
The number 13 is a prime Number

OR

OUTPUT :

Enter a number :12
The number 12 is not a prime Number