I am sure you know what a square prism looks like, so I presume your question is about terminology. Just about all mathematicians would agree that definitions should include special cases; so a square is a rectangle, a rectangle is a parallelogram, etc.

However, you may find some non-mathematicians who use the word "rectangle" to mean "non-square rectangle" and they will think the answer to your question is "four" rather than "six".

-RD

PS: The word "oblong" does mean "non-square rectangle". Mathematicians tend to avoid it, because usually if something is true for other rectangles it is also true for squares and we would want to use the more inclusive term.