Formula One comeback king Michael Schumacher has swapped racing numbers with Mercedes team-mate Nico Rosberg for superstitious reasons.

"Michael has a preference for odd numbers," a team spokeswoman said. "He asked if he could be the odd number and we were happy to accept."

She said the governing International Automobile Federation (FIA) had approved the switch, with Schumacher now having number three on his car and Rosberg four, and a new list would be issued in due course.

As a seven-times world champion, Schumacher has spent much of his record-breaking Formula One career with number one on his car.

He won all his titles with odd numbers - five as number one and once with three and five - and retired with 91 wins.

The German's comeback, aged 41 and following an absence of three years, was announced late last month and after compatriot Rosberg - who has yet to win a race - had been announced as the Mercedes team's first signing.

Mercedes took over 2009 champions Brawn, run by Schumacher's friend and former Ferrari technical director Ross Brawn, but Jenson Button took the number one to McLaren.

Since 1973, when drivers were given numbers for the entire season, nobody has started as number four and won the championship.

Thirteen is considered unlucky and not allocated while Britain's Damon Hill raced with the number zero at Williams in 1993 and 1994 because in each year the reigning champion (Nigel Mansell and Alain Prost) had left the sport.

Odd numbers are not Schumacher's only foible.

The German always wore a ceramic amulet, given to him by his wife and with the initials of his family members, when racing for Ferrari.

In 2004, he left it in his hotel in Bahrain and a team member had to rush and collect it before the race, which Schumacher then won. The German said later that the amulet had made "perhaps the decisive difference".

Schumacher said on his website (www.michael-schumacher.de) this week he felt as if he had never retired after testing a GP2 car in southern Spain and was raring to go.

"I am practising since December physically very carefully and feel extremely fresh and fit," he said.

"After my retirement at the end of 2006 I was very happy, I felt relieved, just like freed.

"I enjoyed that feeling because especially in the last two years F1 had demanded a great deal from me - not the racing, that I loved during all the time, but all those things which relate to living under constant observation.

"It did me extremely well to be quiet for those three years. It really is as if my batteries were fully loaded. My energy is back completely," added the German.