214273domain: NAppears in sequencesHyperperfect numbers: k = m*(sigma(k) - k - 1) + 1 for some m > 1.at n=20A007592Hyperperfect numbers: x such that x = 1 + k*(sigma(x)-x-1) for some k > 0.at n=24A034897Nonsemiprime hyperperfect numbers.at n=8A133447