="Christian Lawson-Perfect" <christianperfect@gmail.com> ... people's intuitions on primality. So far, 51 seems to be by the far most "primey" composite, ...
''... the legend of the so-called "Grothendieck prime". In a mathematical conversation, someone suggested to Grothendieck that they should consider a particular prime number. "You mean an actual number?" Grothendieck asked. The other person replied, yes, an actual prime number. Grothendieck suggested, " All right, take 57." ...'' -- http://www.ams.org/notices/200410/fea-grothendieck-part2.pdf Conversely, are there "compositey" primes? Sort of similarly, I've recently become fond of 343 and 2401. Generally, all these might be called "camouflaged numbers" -- their appearance disguises or misleads intuition of their true nature. Primey numbers have many primey substrings, like 3773. Can we quantify how well "primeyness" predicts primality?