19990000

素因数分解:

$2^4\times 5^4\times {\mathrm{1999}}^1$

素因数の和:2027

約数の個数: 50

約数和(自身を含む): 48422000

約数和(自身を除く): 28432000

約数列:

[1, 2, 4, 5, 8, 10, 16, 20, 25, 40, 50, 80, 100, 125, 200, 250, 400, 500, 625, 1000, 1250, 1999, 2000, 2500, 3998, 5000, 7996, 9995, 10000, 15992, 19990, 31984, 39980, 49975, 79960, 99950, 159920, 199900, 249875, 399800, 499750, 799600, 999500, 1249375, 1999000, 2498750, 3998000, 4997500, 9995000, 19990000]

約数ペア:

[(1, 19990000), (2, 9995000), (4, 4997500), (5, 3998000), (8, 2498750), (10, 1999000), (16, 1249375), (20, 999500), (25, 799600), (40, 499750), (50, 399800), (80, 249875), (100, 199900), (125, 159920), (200, 99950), (250, 79960), (400, 49975), (500, 39980), (625, 31984), (1000, 19990), (1250, 15992), (1999, 10000), (2000, 9995), (2500, 7996), (3998, 5000)]