ELI5: Explain Like I'm 5

Harmonic divisor number

Alright kiddo, a harmonic divisor number is a special type of number that has a very cool mathematical property.

Let's start with a regular number. A number like 6 can be divided by different numbers like 1, 2, 3, and 6. These numbers that can divide 6 evenly are called divisors.

Now, a harmonic divisor number is a special type of number where the sum of its divisors, or factors, is a whole number when divided by the number itself. For example, the number 28 has divisors 1, 2, 4, 7, 14, and 28. When we add up all of these divisors (1+2+4+7+14+28) we get 56. And if we divide 56 by 28 we get 2, which is a whole number.

This makes harmonic divisor numbers super interesting to mathematicians because they have this special property that not all numbers have. They also play a role in some areas of mathematics like number theory and geometry.

So that's what a harmonic divisor number is, a special type of number that has factors that add up to a whole number when divided by the number itself. Pretty cool, huh?