For anyone who enjoyed Dangerous Knowledge (the BBC’s 90-minute documentary that takes a close look at four mathematicians – Georg Cantor, Ludwig Boltzmann, Kurt Gödel and Alan Turing), we bring you this -- N Is a Number: A Portrait of Paul Erdős. Filmed in 1993 by director George Paul Csicsery, the documentary revisits the intellectual contributions of Paul Erdös (1913-1996), perhaps the most prolific mathematician of the last century. The Hungarian-born thinker apparently published more papers than any other mathematician in recorded history and solved seemingly unsolvable problems in graph theory and number theory. Run time is 57 minutes. You can purchase a copy online here.