Japanese coins, a plastic bag

2001

photo by Takagi Shigeki

cf. 2620 and 2924 are the amicable pair which Euler found in 1747.

(Two numbers are called amicable if each equals to the sum of the divisors of the other.)

Divisors of 2620: 1 + 2 + 4 + 5 + 10 + 20 + 131 + 262 + 524 + 655 + 1310 = 2924

Divisors of 2924: 1 + 2 + 4 + 17 + 34 + 43 + 68 + 86 + 172 + 731 + 1462 = 2620