#include<bits/stdc++.h>
using namespace std;
#define ll long long
ll X;
const int n=1e6;
const ll I=1e18;
int d[1010000];
ll mu(ll x,ll y){if(x<=I/y)return x*y;return I+1;}
ll qpow(ll a,ll b){
    ll c=1;
    for(;b;b>>=1){
        if(b&1)c=mu(a,c);
        a=mu(a,a);
    }
    return c;
}
bool pri(ll x){
    for(ll i=2;i*i<=x;i++)if(!(x%i))return 0;return 1;
}
int main(){
    scanf("%lld",&X);
    for(int i=1;i<=n;i++)for(int j=1;i*j<=n;j++)d[i*j]++;
    for(int i=1;i<=n;i++)if(qpow(i,d[i])==X){printf("%d\n",i);return 0;}
    ll O=(ll)sqrt(X);
    while(O*O<X)O++;while(O*O>X)O--;
    if(pri(O)){printf("%lld\n",O);return 0;}
    puts("-1");
    return 0;
}