Circular Prime Number

//C Program
//Check if a given number is Circular Prime or not
#include <stdio.h>
#include <math.h>
//Check number is prime or not
int is_prime(int n)
{
  if(n<=1)
  {
    return 0;
  }
  //Base case
  if(n==2 || n ==3 || n==5)
  {
    return 1;
  }
  
  for (int i = n/2; i > 1 ; --i)
  {
    //Check divisibility of a number
    if(n%i == 0)
    {
      return 0;
    }
  }
  
  return 1;
}
//Count the number of digits in number 
int digit_length(int number) 
{ 
  int size = 0; 

  while (number!=0) 
  { 
    number/=10; 

    size++; 
  } 
  return size; 
}


int is_circular_prime(int number) 
{ 
  //Assign the value of how many number of digits are exist in number
  int  size = digit_length(number);

  int auxiliary = number;

  //Variable which control  execution process
  int remainder = 0;

  int divisor = 0;

  while (is_prime(auxiliary)==1) { 

    //Calculate divisor of auxiliary number
    divisor = auxiliary / 10;

    //Calculate remainder of auxiliary number
    remainder = auxiliary % 10; 
    
    //permutation calculation
    auxiliary = (pow(10, size - 1)) * remainder + divisor; 
    
    //When permutation of number is equal to actual number
    //T
    if (auxiliary == number) 
    {
      return 1; 
    }
  } 

  return 0; 
} 
//Function which are handling the request of number is circular prime or not
void circular_prime(int number)
{
  if(is_circular_prime(number)==1)
  {
    //When Yes
    printf("%d Is an Circular Prime Number\n",number);
  } 
  else
  {
    //When No
    printf("%d Is not a Circular Prime Number\n",number);
  }
}

int main() {
  //Test Cases
  circular_prime(71);
  circular_prime(9311);
  circular_prime(23);
  circular_prime(43);
  circular_prime(13);

  return 0;
}

Output

71 Is an Circular Prime Number
9311 Is an Circular Prime Number
23 Is not a Circular Prime Number
43 Is not a Circular Prime Number
13 Is an Circular Prime Number