PERFECT NUMBERS: AN ELEMENTARY INTRODUCTION
JOHN VOIGHT
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] Thenumber6isuniqueinthat6 = 1+2+3, where1, 2, and3arealloftheproper 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. Thoughitisrootedinancienttimes, remarkablythissubjectremainsvery much alive today, harboring perhaps the “oldest unfinished project of mathematics” [17]. This paper surveys the history and elementary results concerning perfect numbers.