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_21961 ( "Voivodeship after 1569" text, "Capital" text, "Year established" real, "Number of powiats" text, "Area (km\u00b2) in 1590 (Lithuanian) Category:Articles with Lithuanian-language external links" real )

### Question ###
How many powiats have mstsislaw as a capital?

### Accurate SQL ###

SELECT "Number of powiats" FROM table_21961 WHERE "Capital" = 'Mstsislaw'