CREATE TABLE table_53479 ("Week" FLOAT, "Date" TEXT, "Opponent" TEXT, "Result" TEXT, "Attendance" FLOAT)

Which Week has an Opponent of san francisco 49ers?
SELECT MAX("Week") FROM table_53479 WHERE "Opponent" = 'san francisco 49ers'
SELECT MAX("Week") FROM "table_53479" WHERE "Opponent" = 'san francisco 49ers'