It is actually called a unique number like 1 because it is the only thing that can go into itself and because when you times itself by itself then you get what the number is. EXAMPLE: 0 times 0 equals 0 1 times 1 equals 1
find a math glossary. there are a set of numbers that are labeled or grouped together. 0 is a number. but it is not divisible by anything. nothing is intangible. some math teachers may label it as an even number. and are teaching this to the students.