Reordering fields in the bibliography drivers is not always very easy, but with the help of the xpatch package we can speed up the process quite a bit.
First we need to wrap the series and number in parentheses
\renewbibmacro*{series+number}{%
\iffieldundef{series}
{}
{\printtext[parens]{%
\printfield{series}%
\setunit*{\addspace}%
\printfield{number}%
\newunit}}}
And then we define a new command to get rid of the series+number macro and then add it in later.
\newcommand*\patchseries[1]{%
\xpatchbibdriver{#1}
{\usebibmacro{series+number}}
{}
{}
{\typeout{Warning: Failed to remove series+number from driver #1.}}
\xpatchbibdriver{#1}
{\usebibmacro{publisher+location+date}}
{\usebibmacro{publisher+location+date}%
\setunit{\addspace}%
\usebibmacro{series+number}}
{}
{\typeout{Warning: Failed to add series+number to driver #1.}}}
Then you just use
\patchseries{book}\patchseries{inbook}
\patchseries{collection}\patchseries{incollection}
\patchseries{proceedings}\patchseries{inproceedings}
for those types you want patched.
MWE
\documentclass[ngerman]{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{babel}
\usepackage{csquotes}
\usepackage[backend=biber,style=authortitle]{biblatex}
\usepackage{microtype}
\usepackage{filecontents}
\begin{filecontents}{\jobname.bib}
@Book{Kafka.2001,
Title = {Die Verwandlung},
Author = {Kafka, Franz},
Publisher = {Philipp Reclam},
Year = {2001},
Address = {Stuttgart},
Number = {9900},
Series = {Reclams Universal-Bibliothek}
}
\end{filecontents}
\addbibresource{\jobname.bib}
\addbibresource{biblatex-examples.bib}
\usepackage{xpatch}
\renewbibmacro*{series+number}{%
\iffieldundef{series}
{}
{\printtext[parens]{%
\printfield{series}%
\setunit*{\addspace}%
\printfield{number}%
\newunit}}}
\newcommand*\patchseries[1]{%
\xpatchbibdriver{#1}
{\usebibmacro{series+number}}
{}
{}
{\typeout{Warning: Failed to remove series+number from driver #1.}}
\xpatchbibdriver{#1}
{\usebibmacro{publisher+location+date}}
{\usebibmacro{publisher+location+date}%
\setunit{\addspace}%
\usebibmacro{series+number}}
{}
{\typeout{Warning: Failed to add series+number to driver #1.}}}
\patchseries{book}\patchseries{inbook}
\patchseries{collection}\patchseries{incollection}
\patchseries{proceedings}\patchseries{inproceedings}
\DeclareFieldFormat{number}{\bibstring{number}~#1}
\begin{document}
\blockcquote{Kafka.2001}{Als Gregor Samsa eines Morgens aus unruhigen Träumen erwachte, fand er sich in seinem Bett zu einem ungeheueren Ungeziefer verwandelt.}.
\nocite{sigfridsson,worman,brandt,baez/article}
\printbibliography
\end{document}
