Empty document, only pagenumber, 500 pages needed

Use a primitive \loop with \repeat and \unless testing.

\documentclass[pagenumber=footright, DIV=20, fontsize=16]{scrartcl}
\usepackage[automark]{scrlayer-scrpage}
\pagestyle{scrheadings}
\ihead{}
\ofoot[\pagemark]{\pagemark}
\chead{}
\cfoot[]{}
\ohead{}


\newcounter{loopcntr}

\begin{document}
\loop\unless\ifnum\value{loopcntr}=500
\mbox{}
\newpage
\stepcounter{loopcntr}% Advance the counter
\repeat

\end{document}

Here's a variant with pgffor and forloop packages:

\documentclass[pagenumber=footright, DIV=20, fontsize=16]{scrartcl}
\usepackage[automark]{scrlayer-scrpage}
\pagestyle{scrheadings}
\ihead{}
\ofoot[\pagemark]{\pagemark}
\chead{}
\cfoot[]{}
\ohead{}

\usepackage{pgffor}
\usepackage{forloop}

\newcounter{loopcntr}

\begin{document}

\foreach \x in {1,...,500} {%
\mbox{}
\newpage
}

\forloop{loopcntr}{1}{\value{loopcntr} < 501}{%
\mbox{}
\newpage
}


\end{document}

\documentclass[pagenumber=footright, DIV=20, fontsize=16]{scrartcl}
\usepackage[automark]{scrlayer-scrpage}
\pagestyle{scrheadings}
\ihead{}
\ofoot[\pagemark]{\pagemark}
\chead{}
\cfoot[]{}
\ohead{}



\begin{document}


\def\x{\ifnum\value{page}<501\mbox{}\clearpage\expandafter\x\fi}
\x

\end{document}

A variant with package multido (50 bytes):

\documentclass[DIV=20, fontsize=16]{scrartcl}
\usepackage{lmodern}
\usepackage[automark]{scrlayer-scrpage}
\pagestyle{scrheadings}
\cfoot{}
\ofoot[\pagemark]{\pagemark}

\usepackage{multido}

\begin{document}

\multido{}{500}{\null\newpage}

\end{document}