21990205

素因数分解:

$5^1\times {\mathrm{109}}^1\times {\mathrm{157}}^1\times {\mathrm{257}}^1$

素因数の和:528

約数の個数: 16

約数和(自身を含む): 26904240

約数和(自身を除く): 4914035

約数列:

[1, 5, 109, 157, 257, 545, 785, 1285, 17113, 28013, 40349, 85565, 140065, 201745, 4398041, 21990205]

約数ペア:

[(1, 21990205), (5, 4398041), (109, 201745), (157, 140065), (257, 85565), (545, 40349), (785, 28013), (1285, 17113)]