Find vectors and \in \mathbb{R}^3 that simultaneously satisfy all of the following:

 is parallel to (2,1,5)
 is perpendicular to (2,1,5)
I understand what each condition means in terms of how it affects the vectors I am trying to find; however, I can't seem to relate them enough to derive the actual vectors. I know that:
and
also that
How do I go about finding the two vectors that satisfy these conditions other than trial and error?
Thanks.