Count all prime nodes of a linked list

// C Program
// Count all prime nodes of a linked list
#include <stdio.h>
 //For malloc function
#include <stdlib.h>

//Linked List Node
struct Node
{
	int data;
	struct Node *next;
};
//Create a node of linked list
struct Node *create_node(int data)
{
	//Create dynamic node
	struct Node *node = (struct Node *) malloc(sizeof(struct Node));
	if (node == NULL)
	{
		printf("Memory overflow\n");
	}
	else
	{
		//Set initial node value
		node->data = data;
		node->next = NULL;
	}
	return node;
}
//Add new node at end of linked list 
void insert(struct Node **head, int data)
{
	struct Node *node = create_node(data);
	if ( *head == NULL)
	{
		*head = node;
	}
	else
	{
		struct Node *temp = *head;
		//Find last node
		while (temp->next != NULL)
		{
			temp = temp->next;
		}
		//Add node at last possition
		temp->next = node;
	}
}
//Display linked list element
void display(struct Node *head)
{
	if (head == NULL)
	{
		printf("\nEmpty linked list\n");
		return;
	}
	struct Node *temp = head;
	printf("\n Linked List : ");
	//iterating linked list elements
	while (temp != NULL)
	{
		printf("  %d", temp->data);
		//visit to next node
		temp = temp->next;
	}
	printf("\n");
}
//Check that whether given number is prime or not
int is_prime(int num)
{
	if (num == 2 || num == 3 || num == 5)
	{
		return 1;
	}
	if (num <= 1 || (num % 2 == 0) || (num % 3 == 0) || (num % 5 == 0))
	{
		return 0;
	}
	int i = 11;
	while ((i *i) <= num)
	{
		if (num % i == 0)
		{
			//When number is divisible of current i value
			return 0;
		}
		else if (num % (i + 2) == 0)
		{
			//When number is divisible of current i + 2 value
			return 0;
		}
		i = i + 6;
	}
	return 1;
}
//Count the number of linked list nodes which is contains  prime values
void count_prime(struct Node *head)
{
	display(head);
	// This are used to count prime nodes
	int counter = 0;
	//Get first node
	struct Node *temp = head;
	printf(" Prime Nodes : [");
	//iterating linked list elements
	while (temp != NULL)
	{
		if (is_prime(temp->data) == 1)
		{
			printf("  %d", temp->data);
			counter++;
		}
		//visit to next node
		temp = temp->next;
	}
	printf("  ]\n");
	//Display the calculated result
	printf(" Total Prime :  %d \n", counter);
}
int main()
{
	struct Node *head = NULL;
	//Create linked list
	insert( &head, 2);
	insert( &head, 4);
	insert( &head, 5);
	insert( &head, 11);
	insert( &head, 12);
	insert( &head, 7);
	insert( &head, 124);
	insert( &head, 31);
	count_prime(head);
	return 0;
}

Output

 Linked List :   2  4  5  11  12  7  124  31
 Prime Nodes : [  2  5  11  7  31  ]
 Total Prime :  5