Ezekiel 43:16

43:16 Now the altar hearth is a perfect square, 21 feet long and 21 feet wide.

Ezekiel 40:42

40:42 The four tables for the burnt offering were of carved stone, 32 inches long, 32 inches wide, and 21 inches high. They would put the instruments which they used to slaughter the burnt offering and the sacrifice on them.