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

using i64 = long long;

int main() {
    cin.tie(nullptr)->sync_with_stdio(false);
    
    auto solve = [&]() {
        i64 n;
        cin >> n;

        i64 ans = n + 1;

        for (int p = 2; p <= 60; p++) {
            i64 low = 2, high = n;
            while (low < high) {
                i64 mid = low + high >> 1;
                i64 x = 1;
                for (int i = 0; i < p; i++) {
                    if (x > n / mid) {
                        x = n + 1;
                    } else {
                        x *= mid;
                    }
                }
                if (x >= n) {
                    high = mid;
                } else {
                    low = mid + 1;
                }
            }
            i64 x = 1;
            for (int i = 0; i < p; i++) {
                if (x > n / low) {
                    x = n + 1;
                } else {
                    x *= low;
                }
            }
            if (x != n) {
                continue;
            }
            int divs = 0;
            for (int i = 1; i * i <= low; i++) {
                if (low % i == 0) {
                    divs++;
                    if (i * i != low) {
                        divs++;
                    }
                }
            }
            if (divs == p) {
                ans = min(ans, low);
            }
        }

        cout << (ans == n + 1 ? -1 : ans) << '\n';
    };

    solve();

    return 0;
}