#include <bits/stdc++.h>

typedef long long ll;
#define int ll

#define pb push_back
#define fi first
#define se second

using namespace std;

int x;
const int N = 1e6+100;
int cnt[N];

int pw(int a, int b)
{
    int r = a;
    for (int i=2; i<=b; i++)
    {
        if (log(r) + log(a) > log(2*x))
            return -1;
        r *= a;
    }
    return r;
}

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

    cin>>x;
    for (int i=1; i<N; i++)
        for (int j=i; j<N; j+=i)
            cnt[j]++;
    for (int i=1; i<N; i++)
        if (pw(i, cnt[i]) == x)
    {
        cout<<i<<"\n";
        exit(0);
    }

    int s = sqrtl(x);
    if (s*s != x)
    {
        cout<<"-1\n";
        exit(0);
    }

    for (int i=2; i*i<=s; i++)
        if (s%i == 0)
    {
        cout<<"-1\n";
        exit(0);
    }
    cout<<s<<"\n";
}