Who is Petrushka from Dead Souls and what is their importance?

Petrushka is Tchitchikov's footman. He is described as a peculiar man, who enjoys reading and finding new words. He dresses in the same clothing every day, and Tchitchikov often yells at him because of the way he smells. Unfortunately, Petrushka has no access to an area in which he can bathe himself.