Catalyzes the transfer of the acetyl group from acetyl coenzyme A to the free amino group of arylamines and hydrazines. Substrates include isoniazid, anisidine, and 4-aminoveratrole, and to a much lesser extent, p-aminobenzoic acid. acetyl-CoA + an arylamine = an N-acetylarylamine + CoA Homodimer and homotetramer. Belongs to the arylamine N-acetyltransferase family. Extended N-terminus.