NBC News reported in June 2001 that there are 571 stoplights along U.S. Route 66.
USS Nautilus (SSN-571) was the world's first nuclear-powered submarine. [Mostow]
The Prime Curios! "Keywords" page offers a "Search our
Curios!" with advanced search options that contains a list
of 571 MySQL Stopwords. [Green]
(There are 2 curios for this number that have not yet been approved by an editor.)