Weird Number Checker

Weird Number Checker is a free online tool used to check if the number is a weird number.

A number that is abundant but not semiperfect is called a weird number. To evaluate whether a number is a weird number, you have to find the sum of the proper divisors. A number is a weird number if the sum of the proper divisors of the number is bigger than the number, but no other subset of the divisors adds up to the number itself.

Interestingly, prime numbers are deficient and so they can never be weird numbers. Multiples of 6 are pseudoperfect and thus none of them can be a weird number.

For example, the number 70 is a weird number because the proper divisors of 70 are 1, 2, 5, 7, 10, 14 and 35, their sum is

1 + 2 + 5 + 7 + 10 + 14 + 35 = 74

74 > 70, and the subset of the sum of the divisors doesn’t amount to 70.

For example, the number 12 is not a weird number.

The the proper factors of 12 are 1, 2, 3, 4 and 6. The sum of them is

1 + 2 + 3 + 4 + 6 = 16

16>12. But the subset of the sum of divisors 2 + 4 + 6 = 12, so it can’t be a weird number.

The procedure to use the weird number checker is as follows: