Prime number program in c using recursion

#include<stdio.h>

int isPrime(int);

int main(){

    int num,prime;

    printf("Enter a positive number: ");
    scanf("%d",&num);

    prime = isPrime(num);

   if(prime==1)
        printf("%d is a prime number",num);
   else
      printf("%d is not a prime number",num);

   return 0;
}

int isPrime(int num){

    static int i=2;

    if(i<=num/2){
         if(num%i==0)
             return 0;
         else{
             i++;
             isPrime(num);
         }
    }

    return 1;
}