CREATE TABLE table_21928 ("Episode #" TEXT, "Season #" FLOAT, "Title" TEXT, "Writer ( s ) " TEXT, "Director" TEXT, "Originalairdate" TEXT)

what was the title of the episode 21a?
SELECT "Title" FROM table_21928 WHERE "Episode #" = '21a'
SELECT "Title" FROM "table_21928" WHERE "Episode #" = '21a'