Finding Given Number is Strong or not?

Protected void CheckNumberIsStrongOrNot()

  {

    int sof=0,n,dn,ctr,prod,rem;

    n = Convert.ToInt32(txtStrong.Text);

    dn=n;

    while(n!=0)

     {

      prod=1;

      ctr=1;

      rem=n%10;

      while(ctr<=rem)

      {

        prod=prod*ctr;

        ctr=ctr+1;

      }

        sof=sof+prod;

        n=n/10;

     }

     if(sof==dn)

      {

       MessageBox.Show("The number entered is strong number");

      }

      else

      {

       MessageBox.Show("The number entered is not a strong number");

      }

 }