What series number garnered 20.64 million viewers?
CREATE TABLE table_18217750_1 (series__number VARCHAR, us_viewers__millions_ VARCHAR)
SELECT series__number FROM table_18217750_1 WHERE us_viewers__millions_ = "20.64"
<s>[INST] Write mssql query to answer the following question given the database schema. Schema: CREATE TABLE table_18217750_1 (series__number VARCHAR, us_viewers__millions_ VARCHAR) Question: What series number garnered 20.64 million viewers? [/INST] SELECT series__number FROM table_18217750_1 WHERE us_viewers__millions_ = "20.64" </s>