#include <bits/stdc++.h>
#define int long long
#define pii pair<int,int>
#define printf(...)
#define mp make_pair
using namespace std;
void solve()
{
    int x;
    cin>>x;
    const int B = LLONG_MAX;
    function<int(int,int)> lift = [&] (int d, int k){
        if(k == 0) return 1LL;
        if(k==1) return d;
        int dd = lift(d, k/2LL);
        if(dd > B/dd) return LLONG_MAX;
        else dd = dd*dd;
        if(k&1LL){
            if(dd > B/d) return LLONG_MAX;
            else dd *= d;
        }
        return dd;
    };
    auto root = [&] (int x, int k) {
        int L = 1, R = 1e9+11;
        while(L<=R){
            int M = (L+R)/2LL;
            if(lift(M, k) > x) R = M-1;
            else L = M+1;
        };
        return R;
    };
    auto divisors = [&] (int x){
        vector<int> cnts;
        for(int d=2; d*d<=x; ++d){
            int cnt = 0;
            while(x%d==0){
                cnt++;
                x/=d;
            }
            if(cnt) cnts.push_back(cnt);
        }
        if(x>1) cnts.push_back(1);
        int ans = 1;
        for(auto cnt:cnts){
            ans *= (cnt+1);
        }
        return ans;
    };
    if(x == 1) {
        cout<<"1 \n";
        return;
    }
    int ans = -1;
    for(int k=2; ; ++k)
    {
        if(root(x, k) == 1) break;
        if(lift(root(x, k), k) == x) {
            if(divisors(root(x, k)) == k)
                ans = root(x, k);
        }
    }
    cout<<ans;
}
signed main()
{
//    freopen("input_00.txt", "r", stdin);
    int T = 1;
//    cin >> T;
    while(T--)
    {
        solve();
    }
}