Code:
#include <stdio.h>
#include <math.h>

void test(const int aIntNumber)
{
	// Test for divisibility
	if(aIntNumber % 7 == 0||
	   aIntNumber % 11 == 0||
	   aIntNumber % 13 == 0)
	{
		printf("\n%d is divisible!\n", aIntNumber);
	}
	else
	{
		printf("\n%d is not divisible!\n", aIntNumber);
	}

	// Calculate the sum of the digits
	int anotherIntNum = aIntNumber;
	int sumOfDigit = 0;
	while(anotherIntNum > 0)
	{
		sumOfDigit += anotherIntNum % 10;
		anotherIntNum = anotherIntNum / 10;
	}
	sumOfDigit += anotherIntNum;
	// Test if the sum of digits of number is even or odd
	if(sumOfDigit % 2 == 0)
	{
		printf("\nsum of digits in %d is even\n", aIntNumber);
	}
	else
	{
		printf("\nsum of digits in %d is odd\n", aIntNumber);
	}
	// Test if the number is prime or not
	int s = (int)sqrt((double)aIntNumber);
	if(aIntNumber > 0 && aIntNumber < 4)
	{
		printf("\n%d is prime!\n", aIntNumber);
	}
	else if(aIntNumber < 0)
	{
		printf("\n%d is not a natural number!\n", aIntNumber);
	}
	else if(aIntNumber > 4)
	{
		for(int i = 4; i < s; i++)
		{
			if(aIntNumber % i == 0)
			{
				printf("\n%d is prime!\n", aIntNumber);
				return;
			}
		}
		printf("\n%d is Not prime!\n", aIntNumber);
	}
	else
	{
		printf("\n%d is Not prime!\n", aIntNumber);
	}

}

int main(int argc, char* argv[])
{
    test(13);

    return 0;
}