#include <bits/stdc++.h>
using namespace std;
typedef long long ll;

bool is_prime(ll x){
    for(ll i = 2;i * i <= x;i ++){
        if(x % i == 0) return 0;
    }
    return 1;
}

void solve(){
    ll n;
    cin >> n;
    int l,r,mid,ans;

    l = 1; r = 1'000'000'000;
    while(l <= r){
        mid = (l + r) >> 1;
        if(1ll * mid * mid <= n){
            ans = mid;
            l = mid + 1;
        }
        else r = mid - 1;
    }
    if(is_prime(ans) && 1ll * ans * ans == n){
        cout << ans << '\n';
        return;
    }

    for(int i = 1;i <= 1000;i ++){
        if(is_prime(i) && 1ll * i * i * i * i * i * i == n){
            cout << i * i << '\n';
            return;
        }
    }

    for(int i = 1;i <= 100000;i ++){
        int cnt = 0;
        for(int j = 1;j * j <= i;j ++){
            if(i % j == 0){
                cnt ++;
                if(i / j != j) cnt ++;
            }
        }
        __int128 cur = 1;
        for(int j = 1;j <= cnt;j ++){
            cur *= i;
            if(cur > n) break;
        }
        if(cur == n){
            cout << i << '\n';
            return;
        }
    }

    cout << -1 << '\n';
}

int main(){
    ios::sync_with_stdio(false);
    solve();
    return 0;
}