If you’ve heard of Felix Klein, it’s probably due to the Klein bottle, that strange four-dimensional object that is the subject of a new video here on The Aperiodical starring Katie Steckles and Matt Parker. Who is Klein and, apart from the bottle, what did he do?
Klein’s Times obituary records that he would point out “with a smile” that his date of birth comprised three squares of primes. So then, I will refer to his birth as taking place on the $( 5^2 )^{\textrm{th}}$ day of the $(2^2 )^{\textrm{th}}$ month in the year $43^2$ in Prussia. You might like to notice that today is the $( 5^2)^{\textrm{th}}$ day of the $( 2^2 )^{\textrm{th}}$ month as well, so it is the 163rd anniversary of Klein’s birth.