Right now there are, I believe, five former/current presidents alive. Has this number ever been higher? If so when and who made up the list?
Yes. There have been three times where there were six concurrently living presidents and former presidents
1861 - Van Buren, Tyler, Fillmore, Pierce, Buchanan, & Lincoln.
1993 - Nixon, Ford, Carter, Reagan, Bush, & Clinton.
2001 - Ford, Carter, Reagan, Bush, Clinton, & Bush.