Multiple choice general knowledge math & puzzles The least perfect square, which is divisible by each of 21, 36 and 66 is: 213444 213442 213441 213445 Reveal answer Fill a bubble to check yourself A Correct answer Explanation The LCM of 21 (3x7), 36 (2^2x3^2), and 66 (2x3x11) is 2^2 * 3^2 * 7 * 11 = 2772. To make it a perfect square, we must multiply by 7 and 11 to pair the factors: 2772 * 77 = 213444.