prog for smith number check in java

import java.io.*;
class pro_smith
{
public void main()throws IOException
{
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
System.out.println("enter numbers");
int n=Integer.parseInt(br.readLine());
int copy=0,rem=0,i,j,sumd=0,sumf=0;
      
       copy=n;
       sumd=sum_digit(copy);
      
       for(i=2;i<=7;i++)
       {
           if(n%i==0)
           {
               if((i!=4)&&(i!=6))
               {
                   sumf=sumf+i;
                   n=n/i;
                   i--;
                }
            }    
        }
               for(i=11;i<=n;i++)
               {
                   if(n%i==0)
                   {
                       copy=i;
                       for(j=11;j<=i;j++)
                       {
                           if(i%j==0)
                           break;
                        }
                        if(j==i)
                        {
                            sumf=sumf+(sum_digit(copy));
                            n=n/i;
                            i--;
                        }
                    }
                }
                if(sumd==sumf)
                System.out.println("smith number");
                else
                 System.out.println("not a smith number");
                }
                public int sum_digit(int a)
                {
                    int rem=0,sum=0;
                   
                        while(a>0)
                        {
                            rem=a%10;
                            sum=sum+rem;
                            a=a/10;
                        }
                        return sum;
                    }
                }