What is the most deaths in a day in history?

The day with the most deaths in human history was 23 January 1556. That was the day of the Shaanxi earthquake in China, which killed about 830,000 people.

https://www.thehealthyjournal.com/faq/what-day-has-the-most-deaths-in-history#:~:text=The%20day%20with%20the%20most,which%20killed%20about%20830%2C000%20people.