I have a question about arrays(K-5)

My question is, what are #'s that can not be arranged in two row arrays called?

Madalyn
Thanks

If you have some cookies and you arrange them side by side in pairs so that you have two rows, then either the two rows have the same length or one row is one cookie longer than the other. In the first case the number of cookies is even, twice the number in one row, and the cookies are in a two row array. If one row is longer than the other then the number of cookies is odd.