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

#define rep(i, a, b) for (int i = (a); i < (b); i++)
#define all(x) begin(x), end(x)
#define sz(x) int((x).size())
using ll = long long;
using pii = pair<int, int>;
using vi = vector<int>;

#ifdef LOCAL
auto operator<<(auto& o, auto x) -> decltype(x.first, o);
auto operator<<(auto& o, auto x) -> decltype(x.end(), o) {
  o << "{";
  for (int i = 0; auto y : x) o << ", " + !i++ * 2 << y;
  return o << "}";
}
auto operator<<(auto& o, auto x) -> decltype(x.first, o) {
  return o << "(" << x.first << ", " << x.second << ")";
}
void __print(auto... x) { ((cerr << x << " "), ...) << endl; }
#define debug(x...) __print("[" #x "]:", x)
#else
#define debug(...) 2137
#endif

__int128 bp(__int128 a, __int128 b) {
  __int128 r = 1;
  while(b) {
    if(b & 1) r = r * a;
    a = a * a;
    b /= 2;
    if(a > 2e18 || r > 2e18) return 2e18;
  }
  return r;
}

int main() {
  cin.tie(0)->sync_with_stdio(0);
  ll x;
  cin >> x;
  if(x == 1) {
    cout << 1 << '\n';
    return 0;
  }

  vector<int> div(1e6 + 10);
  for(int i = 1; i < div.size(); i++) {
    for(int j = i; j < div.size(); j += i) div[j]++;
  }
  
  ll ans = 1e18;

  {
    ll n = sqrt(x);
    while(n * n < x) n++;
    while(n * n > x) n--;
    bool f = true;
    if(n * n == x) {
      for(ll i = 2; i * i <= n; i++) {
        if(n % i == 0) {
          f = false;
          break;
        }
      }
      if(f) {
        ans = n;
      }
    }
  }

  for(ll n = 2; n <= 1e6; n++) {
    __int128 pw = 1;
    if(div[n] <= 60) {
      
      for(int i = 0; i < div[n]; i++) {
        pw = pw * n;
        if(pw > 1e18) break;
      }
      if(pw == x) ans = min(ans, n);
    }
  } 
  if(ans == 1e18) cout << -1 << endl;
  else cout << ans << endl;
}