Pi Day was yesterday, so today mathematicians who swore allegiance to the Dark Side are celebrating something more sinister: Belphegor's Prime.
Belphegor's Prime is a prime number - you know, a number greater than 1 that cannot be wholly divided by any other number besides 1 and itself.
But it's not just any prime number. For one, it's a palindromic prime number. Then, there's the 666 hiding among the zeroes:
The symbol of Belphegor's Prime is an upside down Pi - derived from a bird glyph first seen in the mysterious Voynich Manuscript.
Saint Wolfgang and the Devil by Michael Pacher
Those of you who have read John Milton's Paradise Lost and Victor Hugo's The Toilers of the Sea would recognize Belphegor as one of the seven Princes of Hell and the demon of inventiveness (he's the prince of "Vanity and Sloth" and seduces people by suggesting ingenious inventions will make them rich).
Previously on Neatorama: The Math Book: Milestones in the History of Math