#include<bits/stdc++.h>

using namespace std;

#define int long long 
#define pb push_back
#define F first 
#define S second 
int fpow(int a, int u, int n){
    int ret = 1;
    while(u){
        if(u & 1)
            ret = (__int128)ret * a % n;
        a = (__int128)a * a % n;
        u >>= 1;
    }
    return ret;
}
int isprime(int n){
    if(n < 3 || n % 2 == 0)
    return n == 2;
    int u = n - 1, t = 0;
    while(u % 2 == 0)
        u/=2, t++;
    for(int i=0;i<8;i++){
        int a=rand() % (n - 2) + 2, v = fpow(a, u, n);
        if(v == 1)
            continue;
        int s;
        for(s = 0; s < t; s++){
            if(v == n - 1)
                break;
            v = (__int128)v * v % n;
        }
        if(s == t)
            return 0;
    }
    return 1;
}

int num(int x){
    int ans=0;
    for(int j=1;j*j<=x;j++){
        if(x%j) continue;
        if(j*j==x) ans++;
        else ans+=2;
    }
    return ans;
}

__int128 po(int x, int id){
    __int128 ans=1;
    for(int i=1;i<=id;i++) ans*=x;
    return ans;
}
void solve(){
    int x;
    cin>>x;
    if(x==1){
        cout<<"1\n";
        return;
    }
    if(isprime(x)){
        cout<<"-1\n";
        return;
    }
    int t=sqrt(x);
    while(t*t<=x) t++;
    while(t*t>x) t--;
    int ans=3e18;
    if(num(t)==2&&t*t==x) ans=t;
    
    int h=3;
    for(int i=1000000;i>=2;i--){
        while(po(i, h)<x) h++;
        if(po(i, h)!=x) continue;
        if(num(i)==h) ans=i;
    }
    if(ans==3e18) ans=-1;
    cout<<ans<<"\n";
}
signed main(){
    ios::sync_with_stdio(0);cin.tie(0);
    solve();
    return 0;
}