The answer's just near the problem. Trust me

$7^{9999}$ has $9999+1=10000$ factors.

Also, $7^n \leq 10^6$ , using logarithms base $10$ :

$\log 7^n = \log 10^6$

$n \log 7= 6\log 10$

$n \log 7= 6$

$n=\frac{6}{\log 7}$

but $\log 7<1$

$\Rightarrow$ $n$ is greater than $5$ , try with $7$ and $7^7<1000$ so the answer is $10000-8=\boxed{9992}$

$7^{9999}$ has 10000 factors, of the form $7^k$ for $k=0,...,9999$ . The first eight, $7^k$ for $k=0,...7$ are less than 1000000, with $7^7=823543$ , so that the remaining $\boxed{9992}$ are greater than 1000000.

Ditto otto i used the same method