indexerror and optimization

[mcrazy1111]

Please post the error code, in it's entirety, between the error tags. This helps in determining where the problem lies.

Error:
123
3
41
Traceback (most recent call last):
  File "/home/atharva/PycharmProjects/untitled/ad.py", line 17, in <module>
    if(x%k[p]==0):
IndexError: list index out of range

This was the error, but I sorted it by using

for p in range (0,len(k)):

at line 16.
The optimisation problem still persists.
If I enter something like 12212, I get an answer. But something like 600851475143 just takes too long(still running) that number is the problem input. Thanks for the reply.