====== Prime Numbers ======

A number that has no positive integer divisors other than one and itself is called a **normal number**.

===== Prime Numbers Among Themselves =====

At least two integers that have no positive common integer divisor other than 1 are called **primes between them**.

  * 6 and 7 are prime between them.
  * 2, 3 and 5 are prime between them.
  4, 9, 13, 27 are prime between them.

<WRAP tip round>
> With 1, all numbers are prime between them.

> Consecutive counting numbers are prime between themselves.

> Not all numbers that are prime between each other have to be prime numbers.
</WRAP>