The number recurs in the round of eighty-four thousand. Buddhist tradition holds that the Buddha taught eighty-four thousand dharmas, doctrines, as antidotes to the eighty-four thousand defilements of sentient beings, the figure standing for an inexhaustible variety of paths suited to every disposition. The emperor Ashoka is said to have built eighty-four thousand stupas to enshrine the relics of the Buddha across his realm, a legendary count expressing totality rather than a census. In all these uses eighty-four and its multiples signify not a precise tally but a completeness so large as to be effectively without limit, a characteristically Indian way of saying all.
Eighty-four factors as 2^2 x 3 x 7 and carries 12 divisors in all. Summing its proper divisors gives 140, more than the number itself, which makes it an abundant number in the classical sense the Pythagoreans used to sort integers into deficient, perfect and abundant classes.
The genuine Pythagorean number philosophy that this modern chart borrows its name from left no writings of its own: Pythagoras and his early followers taught only by mouth, and what survives of their number theory comes instead through Nicomachus of Gerasa, whose Introduction to Arithmetic of the first century CE became the standard authority for a thousand years, and through Iamblichus, who drew on Nicomachus two centuries later; neither wrote anything resembling a name-and-birthdate numerology.