Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_name_16 (assets__us INTEGER, company VARCHAR, revenues__us$_billion_ VARCHAR)

### Question ###
What are the smallest assets with a Company of piraeus bank, and a Revenue (US$ billion) smaller than 3.9?

### Accurate SQL ###

SELECT MIN(assets__us) AS $_billion_ FROM table_name_16 WHERE company = "piraeus bank" AND revenues__us$_billion_ < 3.9