临时代码。

 1 /**
 2 6700417
 3 **/
 4 #include<iostream>
 5 #include<stdio.h>
 6 #include<cstring>
 7 #include<cstdlib>
 8 #include<algorithm>
 9 using namespace std;
10 
11 typedef unsigned long long LL;
12 
13 LL Euler(LL n)
14 {
15     LL i,temp=0;
16     for(i=2;i*i<=n;i++)
17     {
18         if(n%i==0)
19         {
20             while(n%i==0)
21                 n=n/i;
22             if(i>temp) temp = i;
23         }
24     }
25     if(n>temp) temp = n;
26     printf("%llu\n",temp);
27 }
28 int main()
29 {
30     Euler(18446744073709551615);
31     return 0;
32 }