Prime divisor

#include <bits/stdc++.h>
#define wrench786 ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define ll long long
#define PI (acos(-1.0))
#define LIMIT 1000000000
using namespace std;

vector<int>dum(50009,0);
vector<int>prime;
vector<int>divisors;

void sieve(){
    int i,j;
    prime.push_back(2);
    for(i=3;i*i<50009;i+=2){
        if(!dum[i]){
            for(j=i*i;j<50009;j+=i){
                dum[j]=1;
            }
        }
    }
    for(i=3;i<50009;i+=2){
        if(!dum[i]){
            prime.push_back(i);
        }
    }
}

ll int pf(ll int n){
    ll int i,divisor=1,co=0,sqt=sqrt(n);
    for(i=0;prime[i]<=sqt;i++){
        if(n%prime[i]==0){
            co=1;
            while(n%prime[i]==0){
                n/=prime[i];
                co++;
            }
            divisor*=co;
        }
        sqt=sqrt(n);
    }
    if(n>1){
        divisor*=2;
    }
    return divisor;
}
int main(){
    wrench786

#ifndef ONLINE_JUDGE
    clock_t tStart = clock();
    freopen("input.txt", "r", stdin); freopen("output.txt", "w", stdout);
#endif

    sieve();
    // int n,a,b;
    // ll int i,x;
    // divisors.push_back(0);
    // divisors.push_back(1);
    // divisors.push_back(2);
    // divisors.push_back(2);
    // for(i=4;i<=10000000;i++){
    //     x = pf(i);
    // }
    // for(i=0;i<1000;i++){
    //     cout<<divisors[i]<<" ";
    // }
    cout<<pf(12)<<endl;


#ifndef ONLINE_JUDGE
    fprintf(stderr, "\n>> Runtime: %.10fs\n", (double) (clock() - tStart) / CLOCKS_PER_SEC);
#endif

}