mind the gap or devil’s haircut in my mind

Via TYWKIWDBI (scroll all the way through his Divertimento and let yourself get distracted), we learn of the of the property of symmetry or palindromicity in figures, called Scheherazade numbers by Buckminster Fuller for the leading stories that they tell after the character in 1001 Arabian Nights.
One thousand and one is too a palindrome but not a prime number but another, much larger named-number that shares both properties was named by science columnist Clifford A. Pickover Belphegor’s Prime. In long form, the number which reads the same forward or backward would be one quintillion, sixty-six billiard, six-hundred billion and one or 1000000000000066600000000000001 or easier to recall as one followed by thirteen zeros on each side with the Number of the Beast at the centre. For all these cameo appearances of superstitious numbers (notationally represented by an upside down π) is named after one of the seven demonic princes of Hell (Hebrew for Lord of the Gap), characterised by John Milton in Paradise Lost as the devil that curses man with inquisitiveness and ingenuity—considered sinful as looking for short-cuts is the way of pride and sloth.