Group whose order has at most two prime factors

Definition
A group whose order has at most two prime factors is a finite group such that there are at most two prime numbers which divide the order of the group. In other words, the order of the group has the form $$p^aq^b$$ where $$p,q$$ are prime numbers and $$a,b$$ are nonnegative integers.

Stronger properties

 * Trivial group
 * Group of prime power order
 * Shmidt group

Weaker properties

 * Solvable group: