Product of unique prime factors of a number

Given a number n, we need to find the product of all of its unique prime factors. Prime factors: It is basically a factor of the number that is a prime number itself. 
Examples : 
 

Input: num = 10
Output: Product is 10
Explanation:
Here, the input number is 10 having only 2 prime factors and they are 5 and 2.
And hence their product is 10.

Input : num = 25
Output: Product is 5
Explanation:
Here, for the input to be 25 we have only one unique prime factor i.e 5.
And hence the required product is 5.

Method 1 (Simple) 
Using a loop from i = 2 to n and check if i is a factor of n then check if i is prime number itself if yes then store product in product variable and continue this process till i = n.
 

22

Time Complexity: O(n²) 
Auxiliary Space: O(1)

Method 2 (Efficient) 
The idea is based on Efficient program to print all prime factors of a given number
 

22

Time Complexity: O(?n log n) 
Auxiliary Space: O(1)

Please suggest if someone has a better solution which is more efficient in terms of space and time.