I've learned that
$\mathcal{R}$ is commutative → $\mathcal{R}[X]$ is commutative
$\mathcal{R}$ has no zero divisors → $\mathcal{R}[X]$ has no zero divisors
$\mathcal{R}$ is unital → $\mathcal{R}[X]$ is unital
$\mathcal{R}$ is factorial → $\mathcal{R}[X]$ is factorial
$\mathcal{R}$ is Noetherian → $\mathcal{R}[X]$ is Noetherian
Which other properties of a polynomial ring are inherited from its coefficient ring?
List of properties from the comments and answers below (without credits):
$\mathcal{R}$ is reduced → $\mathcal{R}[X]$ is reduced
$\mathcal{R}$ is Abelian → $\mathcal{R}[X]$ is Abelian
$\mathcal{R}$ is nonsingular → $\mathcal{R}[X]$ is nonsingular
$\mathcal{R}$ is 2-primal → $\mathcal{R}[X]$ is 2-primal
$\mathcal{R}$ is Armendariz → $\mathcal{R}[X]$ is Armendariz
$\mathcal{R}$ has characteristic $n$ → $\mathcal{R}[X]$ has characteristic $n$
$\mathcal{R}$ has finite Krull dimension → $\mathcal{R}[X]$ has finite Krull dimension
$\mathcal{R}$ has finite global homological dimension → $\mathcal{R}[X]$ has finite global homological dimension