Naming numbers according to some property or characteristic that they possess is a legitimate — albeit egotistic — activity of some mathematicians. (See Keith Numbers for a simple and elegant example.) Another interesting name category that I have recently learned about is called “Niven Numbers”. These are merely numbers that are divisible by the sum [...]
[The following item appeared in the "From the File" section of The ARITHMETIC TEACHER, October 1983, p. 53. Later it was referenced in other NCTM publications.] Here is a novel activity that can be used with selected dates—for example, March 27, 1981—which might be introduced to the class in the following way: “Today is a [...]