How to separate character and number part from string?

private void demo()
       {
           string cell = "4567rs";
           int row, a = getIndexofNumber(cell);
           string Numberpart = cell.Substring(a, cell.Length - a);
           row = Convert.ToInt32(Numberpart);
           string Stringpart = cell.Substring(0, a);
       }

       private int getIndexofNumber(string cell)
       {
           int indexofNum=-1;
           foreach (char c in cell)
           {
               indexofNum++;
               if (Char.IsDigit(c))
               {
                   return indexofNum;
               }
            }
           return indexofNum;
       }