A novel that satirises Adolf Hitler and the personality cult that once surrounded him has topped the bestselling lists in Germany – and posed the awkward question as to whether readers are laughing at him or with him.

He's Back (Er Ist Wieder Da), a first novel by Timur Vermes, makes its impact before it is even opened, with a cover which depicts Hitler's block-like black parted hair, squeezing the title into the shape of his trademark square moustache. The hefty €19.33 (£16.64) price tag is a none-too subtle reference to the year the Nazi party leader came to power in Germany.

Vermes, a 46-year-old ghostwriter, says the confrontational nature of the book, which has so far sold over 400,000 copies, and tens of thousands of audiobooks, is deliberate at a time when Germans appear to be obsessed by him.

"The fact is we have too much of a stereotype of Hitler," he told German media. "He's always the monster and we can be comforted by the fact that we're different from him. But in reality he continues to spark real fascination in people, just as he did back then when people liked him enough to help him commit crimes."

In the novel Hitler awakes in Berlin in the summer of 2011 having fallen asleep in 1945, in a deliberate parallel with the German fairytale Sleeping Beauty. He becomes a media celebrity – including getting a role on a Turkish-German TV show – before entering politics where he campaigns against dog muck and speeding.

"I want to show that Hitler would have a chance to succeed nowadays just as he did back then, just in another way," said Vermes.

Sales of the 400-page book are riding on the wave of commemorations to mark the 80th anniversary of Hitler's rise to power and it has beaten novels by Paulo Coelho and Ken Follett to steal the top slot in Germany's book charts. Seventeen foreign licences have so far been sold, as well as the film rights. It is due to be published in Britain later this year.

But it has triggered a mixed response by critics. "We laugh but it's a laugh that sticks in the throat," wrote Die Süddeutsche Zeitung.

Germany, it adds, "has a Hitler fixation which has taken on almost manic proportions. Hitler poses in reliable frequency on magazine covers, wanders like a ghost … through the TV channels … Vermes satirises this 'Hitleritis', but his novel draws on it as well and even lends it a new dimension, that of not laughing about Hitler, but with Hitler."