Grigory Perelman can't decide if he wants the money.

"He said he would need to think about it," said James Carlson, who telephoned Perelman with the news he had won the Millennium Prize awarded by the Clay Mathematics Institute of Cambridge, Mass.

Carlson said he wasn't too surprised by the apparent lack of interest from Perelman, a reclusive genius who has a history of refusing big prizes.

In 2006, Perelman made headlines when he stayed away from the ceremony in Madrid where he was supposed to get a Fields Medal, often called the Nobel prize of mathematics. He remained at home in St. Petersburg instead.

As for the new prize, Perelman (PER-il-mahn) told a local television station he hasn't made a decision on whether to accept the money, and that Carlson's institute will be the first to know when he does.

Sergei Rukshin, Perelman's high school math teacher, told The Associated Press on Monday that Perelman is still unsure whether to accept it.

"I know that this time he is seriously thinking about whether he will accept the prize. He still has some time," Rukshin said. The awards ceremony is in June.

Rukshin said Perelman has been without work for four years and has declined all job offers. He previously worked at the Steklov Mathematics Institute.

"As far as I know, after there was so much media attention ... he did not want to be a public person and to look like an animal in the zoo," Rukshin said.

He said he had encouraged Perelman to accept the prize to provide for himself and his elderly mother.

Technically, the award is a done deal.