直接套约数之和公式，10/14

#include <iostream>
#include <cstring>
#include <algorithm>
using namespace std;
#define int long long
const int mod = 9901;
int a,b;
typedef pair<int, int> PII;
vector<PII> ans;

signed main()
{
    cin>>a>>b;
    int x = a,res = a;
    for(int i = 2;i<=x/i;i++)
    {
        if(res % i == 0)
        {
            int num = 0;
            while(res % i == 0)
            {
                num++;
                res /= i;
            }
            //cout<<i<<" "<<num<<endl;
            ans.push_back({i,num * b});
        }
    }
    if(res > 1)ans.push_back({res,b});

    int result = 1;
    for(auto item:ans)
    {
        int p = item.first,num = item.second;
        int tmp = 1;
        for(int i = 0;i<num;i++)tmp = (tmp * p % mod + 1) % mod;
        result = result * tmp % mod;
    }
    if(a == 0)result = 0;
    if(b == 0)result = 1;
    cout<<result<<endl;
    return 0;
}

用等比公式快速求和+快速幂

#include <iostream>
#include <cstring>
#include <algorithm>
using namespace std;
#define int long long
const int mod = 9901;
int a,b;
typedef pair<int, int> PII;
vector<PII> ans;

int qmi(int a,int b)
{
    int res = 1;
    while(b)
    {
        if(b & 1)res = res * a % mod;
        b >>= 1;
        a = a * a % mod;
    }
    return res;
}
signed main()
{
    cin>>a>>b;
    int x = a,res = a;
    for(int i = 2;i<=x/i;i++)
    {
        if(res % i == 0)
        {
            int num = 0;
            while(res % i == 0)
            {
                num++;
                res /= i;
            }
            //cout<<i<<" "<<num<<endl;
            ans.push_back({i,num * b});
        }
    }
    if(res > 1)ans.push_back({res,b});

    int result = 1;
    for(auto item:ans)
    {
        int p = item.first,num = item.second;
        int tmp = 1;
        //for(int i = 0;i<num;i++)tmp = (tmp * p % mod + 1) % mod;
        if((p - 1) % mod == 0)
        {
            tmp = (num + 1) % mod;
        }
        else
        {
            tmp = (qmi(p,num+1) - 1) % mod * qmi((p-1),mod-2) % mod;
        }
        result = result * tmp % mod;
    }
    if(a == 0)result = 0;
    if(b == 0)result = 1;
    cout<<(result % mod + mod) % mod<<endl;
    return 0;
}