What day of the week was November 21, 1905?

The day of the week November 21st, 1905 fell on was a Tuesday.

There were 34 days until Christmas.

Albert Einstein's paper the "Does the Inertia of a Body Depend Upon Its Energy Content?", is published in the journal Annalen der Physik. This paper reveals the relationship between energy and mass. This leads to the mass–energy equivalence formula E = mc².