Is the number 999 the sign of the devil?

According to Robert Langdon in "Angels & Demons", 999 (666 upside down) is the true sign of the devil. Herbert Cane understands this. As a minion of the demons controlling the earth (the super-rich), he blatantly uses 999 as the mantra of his presidential campaign. Plan 999 serves the devil by making the richest few even richer at the expense of everyone else.