Details aside, it’s pretty clear Amazon’s Kindle department enjoyed a strong holiday season. The company said it sold “well over” 1 million Kindle units each week of December, which would be “well over” 4 million Kindles counting the four weeks between Thanksgiving and Christmas.

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Of course, we still don’t know exactly how many were sold and we don’t know the breakdown between sales of the Kindle e-readers and sales of the Kindle Fire, although Amazon (NSDQ: AMZN) did say that it sold “millions” of Kindle Fires and that the tablet has been the best-selling product across all of Amazon’s offerings—electronic and otherwise—since it made its debut in November. And more Kindle Touch units were sold than regular Kindles, according to the company’s press release.

Amazon also noted that the best-selling and fourth-best selling books on Kindles in 2011 involved books written by authors using its Kindle Direct Publishing system. Darcie Chan (The Mill River Recluse) and Chris Culver (The Abbey) enjoyed that distinction, although Amazon (somewhat understandably in this case) didn’t elaborate on how much money they made.