Even perfect polynomials over $F_2$ with four prime factors

A perfect polynomial over the binary field ${\text{F}}_2$ is a polynomial $A \in \F_2[x]$thatequalsthesumofallitsdivisors\mathrm{.}If$\gcd(A,x^2-x) \neq 1$thenwecall$A$even\mathrm{.}Thelistofallevenperfectpolynomialsover$\F_2$ with at most 3 prime factors in known. The object of this paper is to give the list of all even perfect polynomials over ${\text{F}}_2$ with four prime factors. These are all the known perfect polynomials with four prime factors over ${\text{F}}_2$.