#include<bits/stdc++.h>
using namespace std;
#define cs const
#define re register
#define pb push_back
#define pii pair<int,int>
#define ll long long
#define fi first
#define se second
#define bg begin
#define gc getchar
inline int read(){
	char ch=gc();
	int res=0;bool f=1;
	while(!isdigit(ch))f^=ch=='-',ch=gc();
	while(isdigit(ch))res=(res+(res<<2)<<1)+(ch^48),ch=gc();
	return f?res:-res;
}
template<typename tp>inline void chemx(tp &a,tp b){(a<b)?(a=b):0;}
template<typename tp>inline void chemn(tp &a,tp b){(a>b)?(a=b):0;}

cs int N=1000005;

int d[N];





int main(){
	#ifdef Stargazer
	freopen("1.in","r",stdin);
	#endif
	ll x;cin>>x;
	for(int i=1;i<N;i++)
	for(int j=i;j<N;j+=i)d[j]++;
	if(x==1){cout<<1<<'\n';return 0;}
	for(int n=2;n<=1e6;n++){
		ll s=1;int ok=0;
		for(int j=1;j<=d[n];j++){
			if(s>x/n)break;
			s=s*n;
			if(s==x&&j==d[n]){ok=1;break;}
		}
		if(ok){
			cout<<n<<'\n';return 0;
		}
	}
	ll t=sqrt(x);
	if(t*t==x){
		for(int i=2;1ll*i*i<=t;i++){
			if(t%i==0){cout<<-1<<'\n';return 0;}
		}
		cout<<t<<'\n';return 0;
	}
	cout<<-1<<'\n';
}