Problem 3:

The prime factors of 13195 are 5, 7, 13 and 29.

What is the largest prime factor of the number 600851475143 ?

```
```import math
pSieve = []
max = math.floor(math.sqrt( 600851475143 ))
l = 0
i=2;
while i<max:
ii = math.floor(math.sqrt( i ))
found = False
j=0
while j<len(pSieve):
if ( pSieve[j] > ii ):
break;
if (i % pSieve[j] == 0):
found = True
break;
j+=1
if found == False:
pSieve.append(i)
if (600851475143 % i == 0):
l=i
i+=1
print l