CREATE TABLE table_50821 ("Model number" TEXT, "sSpec number" TEXT, "Frequency" TEXT, "L2 cache" TEXT, "Mult." TEXT, "Voltage" TEXT, "Socket" TEXT, "Release date" TEXT, "Part number ( s ) " TEXT, "Release price  (  USD  ) " TEXT)

Which part number was used for the Atom Z500 processor?
SELECT "Part number(s)" FROM table_50821 WHERE "Model number" = 'atom z500'
SELECT "Part number(s)" FROM "table_50821" WHERE "Model number" = 'atom z500'