CREATE TABLE table_name_54 (viewership__millions_ INT, broadcast_date VARCHAR)

What is the lowest viewership in millions of the episode broadcast on 7 September 2001?
SELECT MIN(viewership__millions_) FROM table_name_54 WHERE broadcast_date = "7 september 2001"
SELECT MIN("viewership__millions_") FROM "table_name_54" WHERE "7 september 2001" = "broadcast_date"