CREATE TABLE table_21961 ("Voivodeship after 1569" CLOB, "Capital" CLOB, "Year established" FLOAT, "Number of powiats" CLOB, "Area  ( km\\u00b2 )  in 1590  ( Lithuanian )  Category:Articles with Lithuanian-language external links" FLOAT)

How many powiats have mstsislaw as a capital?
SELECT "Number of powiats" FROM table_21961 WHERE "Capital" = 'Mstsislaw'
SELECT "Number of powiats" FROM "table_21961" WHERE "Capital" = 'Mstsislaw'