New York: Michelle Obama's book Becoming has become a massive hit.

Crown Publishing told The Associated Press on Wednesday that the former first lady's memoir has sold more than 1.4 million copies in print and digital formats in the US and Canada in the seven days since it was released on November 13.

Michelle Obama speaks to the crowd as she presents her anticipated memoir "Becoming" during her book tour stop in Washington, on Saturday. Credit:AP

Based on demand from retailers across all channels, the publisher has printed three million hardcover copies in North America.

On its first day, the book sold more than 725,000 copies, making it one of the year's biggest debuts.