# Compute $\int\limits_{x_1}^{x_2} \int\limits_{y_1}^{y_2} \int\limits_{z_1}^{z_2} {1 \over \sqrt{x^2+y^2+z^2}} dx\ dy\ dz$

$$\int\limits_{x_1}^{x_2}\int\limits_{y_1}^{y_2}\int\limits_{z_1}^{z_2} \frac{1}{\sqrt{x^2+y^2+z^2}}\ dx\ dy\ dz$$ where $x_i, y_i, z_i \in \mathbb{R}$

I've tried to do it with command

Integrate[1/Sqrt[x^2+y^2+z^2],{x,x1,x2},{y,y1,y2},{z,z1,z2}]