There are several so-called "self describing" or ["self-descriptive"](https://en.wikipedia.org/wiki/Self-descriptive_number) integers.
An integer is said to be "self-describing" if it has the property that, when digit positions are labeled 0 to N-1, the digit in each position is equal to the number of times that digit appears in the number.
For example, **2020** is a four-digit self describing number:
<ul>
<li> position 0 has value 2 and there are two 0s in the number; </li>
<li> position 1 has value 0 and there are no 1s in the number; </li>
<li> position 2 has value 2 and there are two 2s; </li>
<li> position 3 has value 0 and there are zero 3s; </li>