#include <bits/stdc++.h>

using namespace std;

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

#define fi first
#define se second
#define mp make_pair

bool is_pr(ll p){
    for(ll x = 2; x * 1ll * x <= p; x ++ ){
        if(p % x == 0) return false;
    }
    return true;
}

const int N = (int)2e6 + 10;
int cnt[N];

ll chk;

int main(){
    ll x;
    cin >> x;
    if(x==1){
        cout << "1\n";
        return 0;
    }
    ll l = 1;
    ll r = (ll)2e9;
    ll mid;
    while(l < r){
        mid = (l + r) / 2;
        if(mid * 1ll * mid >= x) r = mid;
        else l = mid + 1;
    }

    ll low = (ll)2e9;
    if(r * 1ll * r == x && is_pr(r)){
        low = r;
    }

    for(int i = 1; i < N; i ++ ){
        for(int j = i; j < N; j += i) cnt[j]++;
        if(i != 1){
            chk=0;
            ll y = x;
            while(y%i==0){
                chk++;
                y/=i;
            }
            if(y==1 && chk == cnt[i]){
                low=min(low, (ll)i);
            }
        }
    }
    if(low > (ll)1e9){
        cout << "-1\n";
    }
    else{
        cout << low << "\n";
    }
    return 0;
}