What was the title of the episode with 5.04 million viewers?
CREATE TABLE "table1_17641206_4" (
  "episode" real,
  "original_title" text,
  "directed_by" text,
  "written_by" text,
  "original_airdate" text,
  "duration" text,
  "viewership" text
);
SELECT "original_title" FROM "table1_17641206_4" WHERE "viewership"='5.04 million';