#include <cassert>
#include <cmath>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <functional>
#include <iostream>
#include <limits>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

using namespace std;

using Int = long long;

template <class T1, class T2> ostream &operator<<(ostream &os, const pair<T1, T2> &a) { return os << "(" << a.first << ", " << a.second << ")"; };
template <class T> ostream &operator<<(ostream &os, const vector<T> &as) { const int sz = as.size(); os << "["; for (int i = 0; i < sz; ++i) { if (i >= 256) { os << ", ..."; break; } if (i > 0) { os << ", "; } os << as[i]; } return os << "]"; }
template <class T> void pv(T a, T b) { for (T i = a; i != b; ++i) cerr << *i << " "; cerr << endl; }
template <class T> bool chmin(T &t, const T &f) { if (t > f) { t = f; return true; } return false; }
template <class T> bool chmax(T &t, const T &f) { if (t < f) { t = f; return true; } return false; }


// floor(a^(1/k))
unsigned long long floorKthRoot(unsigned long long a, unsigned long long k) {
  if (a == 0) {
    return 0;
  } else if (k <= 1) {
    return a;
  } else if (k == 2) {
    unsigned long long b = a, x = 0, y = 0;
    for (int e = (63 - __builtin_clzll(a)) & ~1; e >= 0; e -= 2) {
      x <<= 1;
      y <<= 1;
      if (b >= (y | 1) << e) {
        b -= (y | 1) << e;
        x |= 1;
        y += 2;
      }
    }
    return x;
  } else if (k <= 40) {
    // min x s.t. x^k >= 2^64
    static constexpr unsigned long long HIS[] =
        {0, 0, 4294967296ULL, 2642246, 65536, 7132, 1626, 566, 256, 139, 85, 57,
         41, 31, 24, 20, 16, 14, 12, 11, 10, 9, 8, 7, 7, 6, 6, 6, 5, 5, 5, 5,
         4, 4, 4, 4, 4, 4, 4, 4, 4};
    const int bsr = 63 - __builtin_clzll(a);
    unsigned long long lo = 1ULL << (bsr / k);
    unsigned long long hi = std::min(1ULL << (bsr / k + 1), HIS[k]);
    for (; lo + 1 < hi; ) {
      const unsigned long long mid = (lo + hi) / 2;
      unsigned long long b = mid * mid;
      for (unsigned i = 2; i < k; ++i) b *= mid;
      ((b <= a) ? lo : hi) = mid;
    }
    return lo;
  } else if (k <= 63) {
    return ((1ULL << k) <= a) ? 2 : 1;
  } else {
    return 1;
  }
}


int main() {
  Int X;
  for (; ~scanf("%lld", &X); ) {
    Int ans = -1;
    if (X == 1) {
      ans = 1;
    } else {
      for (Int e = 60; e >= 2; --e) {
        const Int n = floorKthRoot(X, e);
        Int ne = 1;
        for (int i = 0; i < e; ++i) ne *= n;
        if (ne == X) {
          int cnt = 0;
          for (Int d = 1; d * d <= n; ++d) if (n % d == 0) {
            ++cnt;
            if (d != n/d) ++cnt;
          }
          if (cnt == e) {
            ans = n;
            goto found;
          }
        }
      }
     found:{}
    }
    printf("%lld\n", ans);
  }
  return 0;
}