639640

素因数分解:

$2^3\times 5^1\times {\mathrm{15991}}^1$

素因数の和:16002

約数の個数: 16

約数和(自身を含む): 1439280

約数和(自身を除く): 799640

約数列:

[1, 2, 4, 5, 8, 10, 20, 40, 15991, 31982, 63964, 79955, 127928, 159910, 319820, 639640]

約数ペア:

[(1, 639640), (2, 319820), (4, 159910), (5, 127928), (8, 79955), (10, 63964), (20, 31982), (40, 15991)]