A few corrections.
This doesn't account for leap year.
Auschwitz was only active for 2 and a half years
The 4 million estimate was by the Soviets in 1945. It has since been revised to about 1.1 million.
But seeing as that 4 million figure was a part of the broader 6 million figure, and people still use the 6 million figure today, obviously the people who use that figure are either more dishonest or misinformed by comparison.