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

typedef __int128 ll;
ll pw(ll a,ll x){
	ll ret=1;
	for (;x;x>>=1,a=a*a) if (x&1) ret=ret*a;
	return ret;	
}
ll sq(ll x,ll k){
	ll sz=pow(x,1.0/k);
	for (;pw(sz+1,k)<=x;) sz++;
	for (;pw(sz,k)>x;) sz--;
	return sz;
}

ll x;

int main(){
	{
		long long _x;
		cin >> _x;
		x=_x;
		if (x==1){
			cout << 1 << "\n";
			return 0;	
		}
	}
	for (int k=60;k>=2;k--){
		ll n=sq(x,k);
		if (pw(n,k)!=x) continue;
		
		ll d=1;
		{
			ll now=n;
			for (int i=2;i*i<=now;i++){
				if (now%i==0){
					ll cnt=0;
					for (;now%i==0;now/=i) cnt++;
					d=d*(cnt+1);
				}
			}
			if (now>1) d=d*2;
		}
		if (d==k){
			cout << (long long)n << "\n";
			return 0;
		}
	}
	cout << -1 << "\n";
	return 0;
}