Stealthy Numbers
A positive integer $N$ is stealthy, if there exist positive integers $a$, $b$, $c$, $d$ such that $ab = cd = N$ and $a+b = c+d+1$.
For example, $36 = 4\times 9 = 6\times 6$ is stealthy.
You are also given that there are 2851 stealthy numbers not exceeding $10^6$.
How many stealthy numbers are there that don't exceed $10^{14}$?