Echo author ID in author.php

Question

This is probably a super simple question.

But how do I echo the ID of a user on author.php?

I've tried

the_author_meta('ID')

But it didn't seem to want to work. I want to echo it at the end of a URL, for example;

http:///www.domain.com/author/sampleauthor-id

Obviously, where "id" is that particular author's ID

Any ideas?