#include <bits/stdc++.h>
#define rep(i,l,r) for(int i=l; i<=r; i++)
#define IOS {cin.tie(0);cout.tie(0);ios::sync_with_stdio(0);}
using namespace std;

typedef long long ll;
typedef pair<int,int> P;

ll ksj = 2e18, n;

int f(ll a) {
    int ans = 0, flag = 0;
    for (int i = 1; i * i <= a; i++) {
        if (i * i == a) flag = 1;
        if (a % i == 0) {
            ans++;
        }
    }
    return ans * 2 - flag;
}

void check(ll a, int b) {
    ll ans = 1;
    rep (i, 1, b) ans *= a;
    if (ans != n) {
        return;
    }
    // cout << a<<' '<<b;15625
    if (f(a) == b) {
        ksj = min(ksj, a);
    }
}

int main() {
    cin >> n;
    if (n == 1) {
        cout << 1;
        return 0;
    }
    // cout <<n<<"#";
    rep (i, 2, 60) {
        ll t = pow(n, 1.0/i);
        // cout << t <<'\n';
        check(t, i);
        check(t-1, i);
        check(t+1, i);
    }
    if (ksj > 1e18) cout << -1;
    else cout << ksj;

    return 0;
}