CREATE TABLE table_18766 ("Rank" FLOAT, "Place" TEXT, "County" TEXT, "Per Capita Income" TEXT, "Median House- hold Income" TEXT, "Population" FLOAT, "Number of Households" FLOAT)

what's the number of households with per capita income being $16,820
SELECT "Number of Households" FROM table_18766 WHERE "Per Capita Income" = '$16,820'
SELECT "Number of Households" FROM "table_18766" WHERE "Per Capita Income" = '$16,820'