What is wrong this one

Question

A = 1
for x in range (2,600851475143):
flage = True
if(600851475143%x == 0):
for y in range (2,x):
if(x%y == 0):
flage = False
break
if(flage):
A = x
print(A)

Answer 1

What exactly is it supposed to do?

Answer 2

Find the largest prime number less than 600851475143

Answer 3

First thing, it's gonna take a lot of time to execute this code, if you tried to test it in Sololearn, just forget it. Second : what's the logic behind your code after line 4 ??

Answer 4

To find prime numbers