Thread: Finding the highest prime factor of a number with a C program

I created a program which finds the highest prime factor of a number.
But there is a problem in it. It is working fine till 9 digit numbers. After that it is showing weird numbers as answers.

Code:

#include<stdio.h>

int largestprimefactor(unsigned long a)
{
    int i =2 ,largeprimefactor = 2;
    
    while(a!=1)
    {
        if(a%i==0)
        {
            while(a%i==0)
            {
                a = a/i;
                
                printf("%d ",i);
                
                if(i>largeprimefactor)
                {
                    largeprimefactor = i;
                }
            }
        } 
        
        i++;
    }
    
    return largeprimefactor;
}

main()
{
    unsigned long inputnumber;
    
    printf("Enter a number : ");
    scanf("%d",&inputnumber);
    
    printf("\nThe largest prime factor of %d is %d",inputnumber,largestprimefactor(inputnumber));
}

Okay.

I want to use numbers from 0 to 9 digit numbers.