#include <bits/stdc++.h>

using namespace std;
typedef long long ll;

int main() {
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);

	//600851475143
	ll number;
	cin >> number;

	ll root = sqrt(number) + 10;

	vector<bool> isPrime(root, true);

	ll answer = 0;
	bool hasDivisor = false;

	for (ll i = 2; i < root; i++) {
		if (isPrime[i]) {
			for (ll j = i * i; j < root; j += i) {
				isPrime[j] = false;
			}

			//cout << i << " isPrime" << endl;

			//check ok
			if (number % i == 0) {
				answer = max(answer, i);

				while (number % i == 0) {
					number /= i;
				}

				hasDivisor = true;
			}
		}
	}

	answer = max(answer, number);

	cout << (hasDivisor ? answer : number) << endl;
}