#include<bits/stdc++.h>
#define int long long
using namespace std;
int tot = 0,p[1000010],d[1000010],c[1000010];
bool v[1000010];
void init(int n){
	d[1] = 1;
	for(int i = 2; i <= n; i++){
		if(!v[i]){
			p[++tot] = i;
			d[i] = 2;
			c[i] = 1;
		}
		for(int j = 1; j <= tot && i * p[j] <= n; j++){
			v[i * p[j]] = 1;
			if(i % p[j] == 0){
				c[i * p[j]] = c[i] + 1;
				d[i * p[j]] = d[i] / c[i * p[j]] * (c[i * p[j]] + 1);
				break;
			}
			c[i * p[j]] = 1;
			d[i * p[j]] = d[i] * 2;
		}
	}
}
signed main(){
	init(1000000);
	int n;
	scanf("%lld",&n);
	int x = sqrt(n);
	for(int i = 1; i <= 1000000; i++){
		int tmp = 1;
		while(tmp < n && d[i]) tmp *= i,d[i]--;
		if(tmp == n && !d[i]){
			printf("%lld",i);
			return 0;
		}
	}
	if(x * x == n){
		bool f = 1;
		for(int i = 2; i * i <= x; i++){
			if(x % i == 0){
				f = 0;
				break;
			}
		}
		if(f){
			printf("%lld",x);
			return 0;
		}
	}
	printf("-1");
    return 0;
}