I know that much - but just because it's not advertised, doesn't mean you're allowed to use it?  

It's not a typo either - the net in question is 22/8 - https://whois.arin.net/rest/net/NET-22-0-0-0-1/pft?s=22.0.0.0%2F8

It's directly assigned space, I can't find any reference anywhere about subnets within that space that has been re-assigned, or that is in use by anyone else.