Write an efficient script that prints largest Prime number that is smaller than 1,000,000

largest_prime_under.py

def largest_prime_under(n):
    while n >= 2: #exit loop when all iterations have been exhausted
        
        # If a number is not prime, it can be factored into two factors (let's call them x and y). 
        # If both x and y are greater than the square root of n, then x*y > n, 
        # so at least one of those factors must be less than or equal to the square root of n, 
        # and to check if n is prime, we only need to test for factors less than or equal to the square root:
        if all(n % x for x in range(2, int(n ** 0.5 + 1))):
            print (n) #print and break if the test passes
            break
        n -= 1 #iterate to the next lowest number
 
largest_prime_under(1000000)