Tending to talk excessively about oneself. / Believing oneself to be better and more important than others. / (nonstandard, by confusion of the similar words) Egoistical (advocating egoism).

in an egotistic manner

Egotistical.

A person who talks excessively about themself. / A person who believes in his or her own importance or superiority. / (nonstandard, by confusion of the similar words) An egoist (advocate of egoism).

plural of egotist