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

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    ll x;
    cin >> x;
    auto is_prime = [&](ll x) {
        for (int f = 2; f * f <= x; f++) {
            if (x % f == 0) return false;
        }
        return true;
    };

    ll sq = sqrt(x) + 5;
    while (sq * sq > x) sq--;
    if (sq * sq == x && is_prime(sq)) {
        cout << sq << endl;
        return 0;
    }

    const int N = 31622;
    for (int i = 1; i <= N; i++) {
        if (is_prime(i)) {
            ll pp = i * i;
            if (pp * pp * pp == x) {
                cout << pp << endl;
                return 0;
            }
        }
        int cnt = 0;
        for (int f = 1; f * f <= i; f++) {
            if (i % f == 0) {
                cnt++;
                if (i / f != f) {
                    cnt++;
                }
            }
        }

        __int128 pw = 1;
        for (int j = 0; j < cnt; j++) {
            pw *= i;
            if (pw > 1e18) {
                break;
            }
        }

        if (pw == x) {
            cout << i << endl;
            return 0;
        }
    }

    cout << -1 << endl;
    return 0;
}