Factors / Factors of 405

Factors of 405

1, 3, 5, 9, 15, 27, 45, 81, 135, 405

405 breaks into 5 pairs, tested up to √405 ≈ 20.1; each pair multiplies back to 405 exactly. 405's full pair list is (1, 405), (3, 135), (5, 81), (9, 45), (15, 27), for 10 divisors in total. 405's divisors other than 405 itself sum to just 321, 84 below 405: the common deficient case. 405 is odd, digit sum 9 for 405; small divisors of 405 include 3, 5, 9. 405 has 10 divisors; 404 has 6 and 406 has 8, so 405 wins here. 405 divided by its largest divisor, 135, gives 3.