what is the number of the episode in the season that had 5.60 millions of north american spectors?
CREATE TABLE "table1_2866509_1" (
  "no" real,
  "num" real,
  "title" text,
  "directed_by" text,
  "written_by" text,
  "u_s_air_date" text,
  "production_code" real,
  "u_s_viewers_million" text
);
SELECT "no" FROM "table1_2866509_1" WHERE "u_s_viewers_million"='5.60';