A mixture of mathmode and text is always a bit tricky. Since you are not talking about maths specifically, but numbers with units I would suggest you try the siunitx
package with the detect-all=true
option.
\documentclass{scrartcl}
\usepackage[detect-all=true]{siunitx}
\usepackage{upgreek}
\usepackage{bm}
\begin{document}
\textbf{Some text \SI{14}{\micro\meter} $\bm{\times}$ \SI{95}{\micro\metre}.}
\textbf{Some text \SI{14}{$\upmu$\meter} $\bm{\times}$ \SI{95}{$\upmu$\metre}.}
\end{document}
Note how I used the upgreek
package to demonstrate two methods of implementing the µ in µm. Which one you like better is of course up to you. Just don't mix them.
Most mathematical symbols do not come in a bold version, but there a few packages that help with that. I used \bm
here, but also have look at this overview: https://tex.stackexchange.com/a/99286/118712
siunitx
-package for writing numbers with units, e.g.$\SI{14}{\micro\metre}\times\SI{95}{\micro\metre}$
. It provides correct spacing and prints units upright.