In number theory, a perfect number is a positive integer that is equal to the sum of its proper positive divisors, that is, the sum of its positive divisors excluding the number itself (also known as its aliquot sum).

Yes, what could be more perfect than that?

But what's important is that you celebrate your fourth Perfect Day. This is the only one that you'll be able to commemorate properly.

Our calculator gave up trying to work out when your fifth one will be, but we can tell you that you will need to be 91,855 years old to celebrate it.