Adjectives and ordinal numbers

In Swedish, adjectives and ordinal numbers have many things in common.
From a syntactic point of view, for instance, both are used as attributes,
both can be substantivized, etc. There is also a morphological connection,
since the words for "first" and "second" are inflected according to the
noun's gender (with -e or -a) in the same way as most adjectives.

Are such similarities common in natlangs? Should I try to give these two
classes similar features in my conlangs (if I want them to have a
"natural" feel)?

For instance, I am considering an adjectiveless language. Would it be
normal for such a language to not have any proper ordinal numbers either?

  /Fredrik