Catalyzes the formation of acetyl phosphate from acetate and ATP. Can also catalyze the reverse reaction. acetate + ATP = acetyl phosphate + ADP Mg(2+). Can also accept Mn(2+). Metabolic intermediate biosynthesis; acetyl-CoA biosynthesis; acetyl-CoA from acetate: step 1/2. Homodimer. Belongs to the acetokinase family.