It wasn't me, but I would have come up with 33. The four factors of 33 add up to 48.
The four factors of 33 add up to 48.
Well, 18 and 3 (both factors of 36) add up to 21. As well, the factors 12 and 9 add up to 21.
36
The four factors of 33 add up to 48.
The factors of 36 are 1, 2, 3, 4, 6, 9, 12, 18, 36 No two of them add up to 23.
36
The prime factors of 33 are 3 and 11 and the prime numbers of 2 and 31 add up to 33
360
37
609
36