Abstract. This serves as an elementary introduction to the history and theory surrounding even perfect numbers.
One would be hard put to find a set of whole numbers with a
more fascinating history and more elegant properties surrounded
by greater depths of mystery—and more totally useless—than the
perfect numbers.
—Martin Gardner [2]
The number 6 is unique in that 6 = 1+2+3, where 1, 2, and 3 are all of the proper
divisors of 6. The number 28 also shares this property, for 28 = 1 + 2 + 4 + 7 + 14.
These “perfect” numbers have seen a great deal of mathematical study—indeed,
many of the basic theorems of number theory stem from the investigation of the
Greeks into the problem of perfect and Pythagorean numbers [16]. Moreover, it
was while investigating these numbers that Fermat discovered the (little) theorem
that bears his name and which forms the basis of a substantial part of the theory of
numbers. Though it is rooted in ancient times, remarkably this subject remains very
much alive today, harboring perhaps the “oldest unfinished project of mathematics”
[17].
This paper surveys the history and elementary results concerning perfect num-
bers.
1. Early History