human
Considering the provided database schema and associated query, produce SQL code to retrieve the answer to the query. 
###Database Schema: Call sign, Frequency MHz, City of license, ERP W, Class, FCC info
###Question: What is the total frequency mhz of the kgrj call sign, which has an erp w greater than 21,500?
gpt
SELECT COUNT Frequency MHz FROM table WHERE Call sign = kgrj AND ERP W > 21,500