Yes, they are.
21The square root of 441 is 21
441 square root
It is 21
21
441 has two square roots; 21 or -21.
12
21
i21 = square root of (-441)
If the reverse square root of the reverse of square of a number is the number itself then it is Adam Number. For ex., 12 and 21 Take 12 square of 12 = 144 reverse of square of 12 = 441 square root of the reverse of square of 12 = 21 The reverse square root of the reverse of square of 12 = 12, then number itself. Such number is called Adam Number. cool....................
plus or minus 21
length x length = area length = square root of 441= 21 inches