#include <bits/stdc++.h>
#define fi first
#define se second
#define ll long long
#define pl pair<ll, ll>
#define pi pair<int, int>
#define minpq priority_queue<ll, vector<ll>, greater<ll>>
using namespace std;

#if 1
void __print(int x) {cerr << x;}
void __print(long x) {cerr << x;}
void __print(long long x) {cerr << x;}
void __print(unsigned x) {cerr << x;}
void __print(unsigned long x) {cerr << x;}
void __print(unsigned long long x) {cerr << x;}
void __print(float x) {cerr << x;}
void __print(double x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const char *x) {cerr << '\"' << x << '\"';}
void __print(const string &x) {cerr << '\"' << x << '\"';}
void __print(bool x) {cerr << (x ? "true" : "false");}
template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ','; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '['; for (auto &i: x) cerr << (f++ ? "," : ""), __print(i); cerr << "]";}
void _print() {cerr << endl << flush;}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
#define debug(x...) cerr << "*["<<__LINE__<<"]\t"<< #x << " = "; _print(x)
#endif

const ll mod = 1e9 + 7;

template<typename T> bool chkmin(T &a, T b){return (b < a) ? a = b, 1 : 0;}
template<typename T> bool chkmax(T &a, T b){return (b > a) ? a = b, 1 : 0;}
ll gcd(ll a, ll b) {if(b == 0){return a;} return gcd(b, a % b);}

__int128_t inf = (__int128_t)1 << 100;

__int128 read_int128() {
    string str;
    cin >> str;

    __int128 x = 0, f = 1;
    if (str[0] == '-') {
        f = -1;
        str = str.substr(1);
    }

    for (char c : str) {
        x = x * 10 + (c - '0');
    }
    return x * f;
}

ostream& operator<<(ostream& dest, __int128_t value){
    ostream::sentry s( dest );
    if (s) {
        __uint128_t tmp = value < 0 ? -value : value;
        char buffer[128];
        char* d = std::end(buffer);
        do{
            -- d;
            *d = "0123456789"[tmp % 10];
            tmp /= 10;
        } while (tmp != 0);
        if (value < 0) {
            -- d;
            *d = '-';
        }
        int len = end(buffer) - d;
        if (dest.rdbuf()->sputn(d, len) != len) {
            dest.setstate(ios_base::badbit);
        }
    }
    return dest;
}

int main(){
	ios::sync_with_stdio(false);
	cin.tie(0);
	__int128 x = read_int128();
	for (ll i = 60; i >= 2; i --){
		__int128 lx = 1, rx = x;
		__int128 z = -1;
		while(rx >= lx){
			__int128 mid = (lx + rx) / 2;
			__int128 cur = 1;
			for (ll j = 0; j < i; j ++){
				cur *= mid;
				if (cur > x) break;
			}
			if (cur == x){
				z = mid; break;
			} else if (cur > x){
				rx = mid - 1;
			} else{
				lx = mid + 1;
			}
		}
		__int128 cur = 1;
		for (ll j = 0; j < i; j ++){
			cur *= lx;
			if (cur > x) break;
		}
		if (cur == x) z = lx;
		if (z != -1){
			ll cnt = 0;
			for (__int128 j = 1; j * j <= z; j ++){
				if (z % j == 0){
					if (j * j == z) cnt ++;
					else cnt += 2;
				}
			}
			if (cnt == i){
				cout << z << '\n';
				return 0;
			}
		}
	}
	cout << -1 << '\n';
}

/*
Do something instead of nothing!
Print out stuffs / study samples when you cannot find the bug!
*/