3. $[x]$ represents the greatest integer not exceeding the real number $x$. Then, in the Cartesian coordinate system $x O y$, the area of the figure formed by all points $(x, y)$ that satisfy $[x][y]=$ 2011 is $\qquad$
3.4.

Let $[x]=a,[y]=b$, meaning all such points $(x, y)$ form the region
$$
a \leqslant x<a+1, b \leqslant y<b+1
$$

bounded by these inequalities, with an area of 1.
Since 2011 is a prime number, the points $(x, y)$ that satisfy
$$
[x][y]=2011
$$

form 4 regions, each with an area of 1, making the total area 4.