#include<bits/stdc++.h>
using namespace std;
#define L long long
L M = 1e6;
inline L pow_mod(L x, L n) {
  L res = 1;
  for (; n; n >>= 1) {
    if (n & 1) res = res * x;
    x = x * x;
  }
  return res;
}
int main() {
  ios_base::sync_with_stdio(0); cin.tie(0);
  vector<L> primes;
  vector<L> fact(M+1,1);
  for (L i = 2; i <= M; i++) {
    if (fact[i] == 1) {
      primes.push_back(i);
      for (L j = 2 * i; j <= M; j += i) {
        L f = 1;
        L k = j;
        while (k % i == 0) {
          k /= i;
          f++;
        }
        fact[j] *= f;
      }
    }
  }
  L x;
  cin >> x;
  for (double i = 62; i >= 2; i--) {
    L v = round(pow(x, 1/i));
    if (pow_mod(v, i) == x) {
      if (i > 2) {
        if (i == fact[v]) {
          cout << v << endl;
          return 0;
        }
      } else {
        bool succ = true;
        for (L a : primes) {
          if (a != v && x % a == 0) {
            succ = false;
          }
        }
        if (succ) {
          cout << v << endl;
          return 0;
        }
      }
    }
  }
  cout << "-1\n";
}

/*

15625

*/