How many production codes does "number one" have?
CREATE TABLE "table1_2623498_2" (
  "episode_num" real,
  "title" text,
  "directed_by" text,
  "written_by" text,
  "original_air_date" text,
  "prod_code" real
);
SELECT MAX("prod_code") FROM "table1_2623498_2" WHERE "title"='\"Number One\"';