#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ld long double
#define endl '\n'

/*
	Factoring Integers
	Factor any integer such that N * N > n
*/

const int N = 1e5+7;
vector<bool> is_prime;
vector<ll> primes;

void init_factor(){
	is_prime.assign(N+1, true);
	primes.clear();
	is_prime[0] = is_prime[1] = false;
	for(int i=2; i*i<=N; i++)
		for(int j=i*i; is_prime[i] && j<=N; j+=i)
			is_prime[j] = false;
	for(int i=2; i<=N; i++)
		if(is_prime[i]) primes.push_back(i);
}

// factor(420) = [[2,2], [3,1], [5,1], [7,1]]
// factor(74) = [[2,1], [37,1]]
int factor(ll n){
	assert(1LL*N*N > n);
	int v = 0;
	for(int i=1; i*i<=n; i++){
		if(n%i == 0){
		    v++;
		    if(i*i != n) v++;
		}
	}
	return v;
}

int main(){
	ios::sync_with_stdio(false); cin.tie(0);
	init_factor();
	ll x;
	cin >> x;
	if(x==1){
	    cout << 1;
	    return 0;
	}
	ll ans = -1;
	for(ll p=2; p<=1000; p++){
	    ll a = pow((ld)x, (ld)1.0 / (ld)p);
	    // cout << a << "^" << p << endl;
	    if((ll)pow(a, p) == x && factor(a) == p){
	        ans = max(ans, a);
	    }
	    if((ll)pow(a+1, p) == x && factor(a+1) == p){
	        ans = max(ans, a+1);
	    }
	    if((ll)pow(a-1, p) == x && factor(a-1) == p){
	        ans = max(ans, a-1);
	    }
	}
	cout << ans;
}