CREATE TABLE table_21055055_2 (au_air_date VARCHAR, viewers__m_ VARCHAR)

When did the episode seen by is 2.267 million people get aired?
SELECT au_air_date FROM table_21055055_2 WHERE viewers__m_ = "2.267"
SELECT "au_air_date" FROM "table_21055055_2" WHERE "2.267" = "viewers__m_"