Grothendieck Prime

Quoting from the article Comme Appelé du Néant—As If Summoned from the Void: The Life of Alexandre Grothendieck by Allyn Jackson published in Notices of the AMS, Volume 51, Number 10:

One striking characteristic of Grothendieck's mode of thinking is that it seemed to rely so little on examples. This can be seen in 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.”