We explore the class of positive integers n that admit idempotent factorizations n=pq such
that lambda(n) divides (p-1)(q-1), where lambda(n) is the Carmichael lambda function. Idempotent factorizations with p and q prime have received the most attention due to their cryptographic advantages, but there are an infinite number of n with idempotent factorizations containing composite p and/or q.
Idempotent factorizations are exactly those p and q that generate correctly functioning keys in the
RSA 2-prime protocol with n as the modulus. While the resulting p and q have no cryptographic utility and therefore should never be employed in that capacity, idempotent factorizations warrant study in their own right as they live at the intersection of multiple hard problems in computer science and number theory. We present some analytical results here. We also demonstrate the existence of
maximally idempotent integers, those n for which all bipartite factorizations are idempotent. We show
how to construct them, and present preliminary results on their distribution.