CREATE TABLE table_1784514_1 (year_established NUMBER, number_of_powiats VARCHAR2)

What is the latest year established that had 5 powiats?
SELECT MAX(year_established) FROM table_1784514_1 WHERE number_of_powiats = "5 powiats"
SELECT MAX("year_established") FROM "table_1784514_1" WHERE "5 powiats" = "number_of_powiats"