what rank has viewers at 6.45?
CREATE TABLE table_15681686_4 (rank__week_ VARCHAR, viewers__millions_ VARCHAR)
SELECT rank__week_ FROM table_15681686_4 WHERE viewers__millions_ = "6.45"
### Context: CREATE TABLE table_15681686_4 (rank__week_ VARCHAR, viewers__millions_ VARCHAR) ### Question: what rank has viewers at 6.45? ### Answer: SELECT rank__week_ FROM table_15681686_4 WHERE viewers__millions_ = "6.45"