If A = {Prime numbers}, B = {Even numbers}, then $n(A\cap B)=$

Given that the set $A$ is the set of all prime numbers and the set $B$ is the set of all even numbers

The intersection of both sets $A$ and $B$ is $A\cap B$, this set contains the elements of both the sets A and B

it means $A\cap B$ is the set of all even prime numbers 

it implies that $A\cap B=\left\{2\right\}$

Therefore, $n(A\cap B)=\boxed{1}$