1. Observe:
$$
\begin{array}{l}
1 \times 2 \times 3 \times 4+1=5^{2} \\
2 \times 3 \times 4 \times 5+1=11^{2} ; \\
3 \times 4 \times 5 \times 6+1=19^{2} ; \\
\ldots \ldots
\end{array}
$$

Calculate $\sqrt{2020 \times 2021 \times 2022 \times 2023+1}=$
Answer: 4086461