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

int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);

  const int64_t MX = 1e18+1e9;

  auto raise_to_pow = [&](int64_t x, int y)->int64_t {
    int64_t res = 1;
    bool overflowed = false;
    while(y--) {
      if (res > MX/x) {
        overflowed = true;
        break;
      }
      res *= x;
    }
    return overflowed?MX:res;
  };

  auto kth_root = [&](int64_t N, int k) {
    int64_t root = pow(N, 1.0/k);
    while(true) {
      int64_t pw = raise_to_pow(root, k);
      if (pw > N) break;
      root++;
    }
    while(true) {
      int64_t pw = raise_to_pow(root, k);
      if (pw <= N) break;
      root--;
    }
    return raise_to_pow(root, k) == N?root:-1;
  };

  auto factorize = [&](int64_t N) {
    vector<pair<int64_t, int>> res;
    for (int64_t i = 2; i * i <= N; i++) {
      if (N % i == 0) {
        int c = 0;
        while (N % i == 0) {
          N /= i;
          c++;
        }
        res.push_back({i, c});
      }
    }
    if (N != 1) res.push_back({N, 1});
    return res;
  };


  int64_t N;
  cin >> N;
  if (N == 1) {
    cout << 1 << '\n';
    return 0;
  }
  int64_t ans = MX;
  for (int k = 2; k <= 65; k++) {
    int64_t root = kth_root(N, k);
    if (root == -1) continue;
    auto pf = factorize(root);
    int64_t divc = 1;
    for (auto& [p, e] : pf) {
      divc *= (1+e);
    }
    if (divc == k) {
      ans = min(ans, root);
    }
  }
  if (ans == MX) {
    cout << -1 << '\n';
  } else {
    cout << ans << '\n';
  }
}