#include<bits/stdc++.h>

using namespace std;
int d[1000006];
bool checkForP(long long a) {
    //cout << a;
    for (int i = 2; i < min(1000000ll, a); i ++) {
        if (d[i] == i && a % i == 0) {
                //cout << i << endl;
            return false;
        }
    }
    return true;
}

bool check(long long val, int rd) {
    map<int, int> q;
    while (val > 1) {
        q[d[val]] ++;
        val /= d[val];
    }
    int myRd = 1;
    for (auto it : q) {
        myRd *= (it.second + 1);
    }
    return rd == myRd;
}
main() {
    long long n, m, k, ans = 1000001;
    cin >> n;
    if (n == 1) {
        cout << 1;
        return 0;
    }
    for (int i = 2; i < 1000000; i ++) {
        if (!d[i]) {
            for (int j = i; j <= 1000000; j += i) {
                d[j] = i;
            }
        }
    }

     k = sqrt(n);
     int l = min(k + 1, 1000000000ll);//cout << k << " " << << "!!";
     for (k --; k <= l; k ++) {
        if (k * k == n) {
            if (checkForP(k)) {
                ans = k;
            }
         }
     }
    int j = 70;
    for (int i = 2; i <= 1000000; i ++) {
        long long h = i;
        for (int a = 2; a <= j; a ++) {
            if (h < 0 || n / i < h) {
                break;
            }
            h *= i;
            if (n == h) {
                if (check(i, a)) {
                    cout << i;
                    return 0;
                }
                break;
            }
        }
    }

    if (ans == 1000001) {
        cout << -1;
    } else {
        cout << ans;
    }
}