 This works with all perfect numbers 2"p"−1(2"p" − 1) with odd prime "p" and, in fact, with all numbers of the form 2"m"−1(2"m" − 1) for odd integer (not necessarily prime) "m".Owing to their form, 2"p"−1(2"p" − 1), every even perfect number is represented in binary form as "p" ones followed by "p" − 1  zeros; for example,
and
Thus every even perfect number is a pernicious number.Every even perfect number is also a practical number (c.f.