Definitely not Amazon the company doing it, probably one of their AWS customers are using their servers to crawl. Technically not illegal (check local state law, scanning ports for malicious intent can be illegal), but you may want to report those IP address if you find it abusive or not appropriate:
Amazon is a large server / cloud computing solution provider: https://aws.amazon.com.
Might just have apps / bots crawling your site.
Or, Amazon might be doing automated competitive research and looking to take over your niche (just kidding, kind of hah I hope not!)