#include "bits/stdc++.h"

using lint = int64_t;

using namespace std;
const lint linf = lint(1e18) + 10;
const int mod = 998244353;
map<lint,lint> memo;

int countDiv(lint x) {
    set<lint> st;
    for(lint i = 1; i*i <= x; i++) {
        if(x % i == 0) {
            st.insert(i);
            st.insert(x/i);
        }
    }
    return st.size();
}

lint f(lint x) {
    lint ans = 1;
    for(int i = 0; i < countDiv(x); i++) {
        ans *= x;
    }
    return ans;
}

const int ms = 1e6 + 10;

int main() {
    cin.tie(nullptr)->sync_with_stdio(false);
    vector<int>num(ms);
    for(int i=1;i<ms;i++){
        for(int j=i;j<ms;j+=i) num[j]++;
    }
    lint ans = linf;
    lint n;
    cin>>n;
    for(lint i=1;i<ms;i++){
        lint cur = 1;
        for(int j=0;j<num[i];j++){
            if(linf / i < cur) cur = linf;
            else cur = cur * i;
        }
        if(cur == n) ans = min(ans, i);
    }
    lint lo = 1, hi = 1e9 + 2;
    while(lo <= hi){
        lint mid = (lo + hi) / 2;
        if(mid * mid <= n) lo = mid + 1;
        else hi = mid - 1;
    }
    if(hi >= ms && hi * hi == n){
        int d = 0;
        for(lint i=2;i*i<=hi;i++){
            if(hi % i == 0){
                d++;
            }
        }
        if(!d) ans = min(ans, hi);
    }
    if(ans == linf) cout<<"-1\n";
    else cout<<ans<<"\n";

    return 0;
}