A perfect number is a number that is the sum of its proper divisors: $$28 = 1 + 2 + 4 + 7 + 14$$
Is there a name for numbers whose only proper divisors are $1$, $2$, and $N/2$? For example
$6$ is divisible by $1$, $2$, and $3$
$8$ is divisible by $1$, $2$, and $4$
$34$ is divisible by $1$, $2$, and $17$
Is there a name for these numbers?