You clearly do not understand the term

* divisible *.

First that term refers to

**integers**.

So the statement that

is divisible by

means that each of

are integers such that

That means that

**cannot** be divisible by

.

** Do you see why?**
That definition also is used in defining prime numbers: an integer is prime if and only if it has exactly two divisors.

Often even well respected textbooks and commentators (i.e. Keith Devlin the math guy) say that an integer is prime if "it is only divisible by itself and one". But that definition makes one a prime. Do you see why?

BTW: (Thanks to R L Moore for that distinction,)