编写一个Java 应用程序，计算两个大整数的和、差、积和商，并计算一个大整数的因 子个数（因子中不包括1 和大整数本身）。

package ex6_2;
import java.math.BigInteger;

public class BigintegerExample {
    public static void main(String[] args) {
                BigInteger n1=new BigInteger("987654321987654321");
                BigInteger n2=new BigInteger("123456789123456789");
                BigInteger result=null;
                result=n1.add(n2);
                System.out.println("和："+result.toString());
                result=n1.subtract(n2);
                System.out.println("差："+result.toString());
                result=n1.multiply(n2);
                System.out.println("积："+result.toString());
                result=n1.divide(n2);
                System.out.println("商："+result.toString());
                BigInteger m=new BigInteger("123"),
                           COUNT=new BigInteger("0"),
                                ONE=new BigInteger("1"),
                               TWO=new BigInteger("2");
                System.out.print(m.toString()+"的因子有：");
                for(BigInteger i=TWO; i.compareTo(m)<0;i=i.add(ONE)){
                    if((m.remainder(i).compareTo(BigInteger.ZERO))==0){
                        COUNT=COUNT.add(ONE);
                        System.out.print("  "+i.toString());
                    }
                }
                System.out.println(" ");
                System.out.println(m.toString()+"一共有"+COUNT.toString()+"个因子");
            }
    }