757. Stealthy Numbers

A positive integer $N$$N$ is stealthy, if there exist positive integers $a$$a$, $b$$b$, $c$$c$, $d$$d$ such that $ab=cd=N$$ab = cd = N$ and $a+b=c+d+1$$a+b = c+d+1$.
For example, $36=4\times 9=6\times 6$$36 = 4\times 9 = 6\times 6$ is stealthy.

You are also given that there are 2851 stealthy numbers not exceeding ${10}^6$$10^6$.

How many stealthy numbers are there that don't exceed ${10}^{14}$$10^{14}$?

757. 隐形数

若存在正整数 $a$$a$、$b$$b$、$c$$c$、$d$$d$ 满足 $ab=cd=N$$ab = cd = N$ 且 $a+b=c+d+1$$a + b = c + d + 1$，则称该正整数 $N$$N$ 是 隐形数。
例如，$36=4\times 9=6\times 6$$36 = 4\times 9 = 6\times 6$ 是隐形数。

已知：$\le {10}^6$$\leq 10^6$ 的隐形数共有 $2851$$2851$ 个。

$\le {10}^{14}$$\leq 10^{14}$ 的隐形数有多少个？

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