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_21 ( class VARCHAR, frequency_mhz VARCHAR, call_sign VARCHAR )

### Question ###
Which Class has a Frequency MHz larger than 91.7, and a Call sign of k272ec?

### Accurate SQL ###

SELECT class FROM table_name_21 WHERE frequency_mhz > 91.7 AND call_sign = "k272ec"