“I poured my heart and soul into my memoir, and I am grateful to my fans and readers around the world for their unwavering support,” Spears said in a statement released Wednesday by Gallery Books, a division of Simon & Schuster.

The sales figures include pre-orders, print sales, e-books and audiobooks. “The Woman in Me,” released Oct. 24, has been praised by critics as a compelling account of her rise to global fame and her ongoing struggles, notably the conservatorship that for years granted her father control of much of her life.

The singer’s highly-anticipated book, for which she did little publicity beyond posts on her Instagram page, was the top seller of last week. But it’s not the year’s fastest seller. Prince Harry’s memoir “Spare,” which came out in January, sold 1.6 million U.S. copies in its first week.

The audio edition of Spears’ book, read by Oscar-nominated actor Michelle Williams, appears a key factor in the book’s initial success. Williams’ reading of “The Woman in Me” has been highly acclaimed, and according to Gallery, is the fastest selling audio release in the company’s history. The publisher did not immediately announce a specific sales figure for the audiobook.

According to Circana, which tracks around 85% of the print market, “The Woman in Me” sold just under 418,000 copies, far below first week Circana numbers for former President Barack Obama’s “A Promised Land” and former first lady Michelle Obama’s “Becoming” among other memoirs.