We have indeterminateness of type
oo/oo,
i.e. limit for the numerator is
$$\lim_{n \to \infty} n^{2 n} = \infty$$
and limit for the denominator is
$$\lim_{n \to \infty} n! = \infty$$
Let's take derivatives of the numerator and denominator until we eliminate indeterninateness.
$$\lim_{n \to \infty}\left(\frac{n^{2 n}}{n!}\right)$$
=
$$\lim_{n \to \infty}\left(\frac{\frac{d}{d n} n^{2 n}}{\frac{d}{d n} n!}\right)$$
=
$$\lim_{n \to \infty}\left(\frac{n^{2 n} \left(2 \log{\left(n \right)} + 2\right)}{\Gamma\left(n + 1\right) \operatorname{polygamma}{\left(0,n + 1 \right)}}\right)$$
=
$$\lim_{n \to \infty}\left(\frac{n^{2 n} \left(2 \log{\left(n \right)} + 2\right)}{\Gamma\left(n + 1\right) \operatorname{polygamma}{\left(0,n + 1 \right)}}\right)$$
=
$$\infty$$
It can be seen that we have applied Lopital's rule (we have taken derivatives with respect to the numerator and denominator) 1 time(s)