CREATE TABLE table_24571 ("Train No." TEXT, "Train Name" TEXT, "Destination" TEXT, "Category" TEXT, "Frequency" TEXT)

What is the category for trains numbered 16609/16610?
SELECT "Category" FROM table_24571 WHERE "Train No." = '16609/16610'
SELECT "Category" FROM "table_24571" WHERE "Train No." = '16609/16610'