The polyadic integer numbers, which form a polyadic ring, are representatives of a fixed congruence class. The basics of polyadic arithmetic are presented: prime polyadic numbers, the polyadic Euler function, polyadic division with a remainder, etc. are introduced. Secondary congruence classes of polyadic integer numbers, which become ordinary residue classes in the "binary limit", and the corresponding finite polyadic rings are defined. Polyadic versions of (prime) finite fields are introduced. These can be zeroless, zeroless and nonunital, or have several units; it is even possible for all of their elements to be units. There exist non-isomorphic finite polyadic fields of the same arity shape and order. None of the above situations is possible in the binary case. It is conjectured that a finite polyadic field should contain a certain canonical prime polyadic field, defined here, as a minimal finite subfield, which can be considered as a polyadic analogue of GF(p).