[Author] O. I. Reinov [Title] Approximation properties and some classes of operators [AMS Subj-class] 47B10 Hilbert--Schmidt operators, trace class operators, nuclear operators, p-summing operators, etc. [Abstract] Among others, we consider in detail some questions around the properties of operators with $p$-nuclear adjoints. For $p=1,\infty$, we give also new examples of operators, which can not be factored through $L_p$-spaces, but whose adjoints factor compactly through $l_{p'}$-spaces. We show that, for any $p\in[1,\infty]$, all Banach spaces have the (new) so called approximation property $AP(l_p)$, connected with the compact factorizatons of operators through $l_p$, if and only if every operator, whose adjoint factors compacly through $l_{p'}$, can be factored (compactly) through the space $l_p$. [Comments] AmSTeX, 60 pp., Russian [Contact e-mail] orein@orein.usr.pu.ru