#include <bits/stdc++.h>
#define ff first
#define ss second
using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

ll N, ans=1e18;

ll mypow(ll x, int k)
{
	__int128 ret=1;
	for(int i=0; i<k; i++)
	{
		ret*=x;
		if(ret>N) return N+1;
	}
	return ret;
}

ll f(int K)
{
	ll lo=0, hi=1e9+10;
	while(lo+1<hi)
	{
		ll mid=lo+hi>>1;
		if(mypow(mid, K)<=N) lo=mid;
		else hi=mid;
	}
	if(mypow(lo, K)!=N) return -1;
	return lo;
}

int main() {
	cin.tie(0); ios_base::sync_with_stdio(0);

	scanf("%lld", &N);
	if(N==1) return !printf("1\n");

	for(int i=100; i>=2; i--)
	{
		ll t=f(i);
		if(t==-1) continue;

		int cnt=0;
		for(ll j=1; j*j<=t; j++)
		{
			if(t%j) continue;
			if(j*j==t) cnt++;
			else cnt+=2;
		}
		if(cnt==i) return !printf("%lld\n", t);
	}
	printf("-1\n");
}