Cognizant/Accenture/Kronos 2016 interview question - get all smith numbers upto 10000

SOURCE CODE

/*program to find out all smith numbers upto 10000 though it'd work for further range as well*/
#include <stdio.h>
#include <stdbool.h>
#include <math.h>

//function're declared here
int sum_of_digits(int,int);
int sumofPrimeFactors(int);
bool checkMorethanonedigit(int);
bool checkPrimeNumber(int);

//main function defined here
int main()
{
int i,range,n,k;
printf("Enter the range = ");
scanf("%d",&range);
for(i=4;i<=range;i++)
{
   if(checkPrimeNumber(i)) continue;
   if(sum_of_digits(i,0) == sumofPrimeFactors(i))
   {
      printf("%d ",i);
   }
}   
    return 0;
}

//function definition starts here
//check the prime factor has more than 1 digit or not
bool checkMorethanonedigit(int n)
{
if(n > 9)
{
return true;
}
else
{
return false;
}
}

//get the summation of all prime factors of the number
int sumofPrimeFactors(int n)
{
int i,sum=0;
    while (n%2 == 0)
    {
    sum += 2;
        n = n/2;
    }
    for (i = 3; i <= sqrt(n); i = i+2)
    {
        while (n%i == 0)
        {
        if(checkMorethanonedigit(i))
        {
        sum += sum_of_digits(i,0);
        }
        else sum += i;
            n = n/i;
        }
    }
    if (n > 2)
    {
    if(checkMorethanonedigit(n))
    {
    sum += sum_of_digits(n,0);
    }
    else sum += n;
    }
return sum;
}

//get summation of digits of a number if needed
int sum_of_digits(int i,int sum)
{
   int j;
   while (i > 0)
   {
   j = i % 10;
   i = i / 10;
   sum=sum+j;
   }
   return sum;
}

//check a number prime or not
bool checkPrimeNumber(int num)
{
    int j, flag;
    flag = 0;
    for (j = 2; j <= num / 2; j++)
    {
        if ((num % j) == 0)
        {
            flag = 1;
            break;
        }
    }
    if (flag == 0) return true;
    else return false;
}