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_79685 ( "Call sign" text, "Frequency MHz" real, "City of license" text, "ERP W" real, "Class" text, "FCC info" text )

### Question ###
What is the total frequency mhz of the kgrj call sign, which has an erp w greater than 21,500?

### Accurate SQL ###

SELECT COUNT("Frequency MHz") FROM table_79685 WHERE "Call sign" = 'kgrj' AND "ERP W" > '21,500'