January 21 is the 21st day of the year
It is also Sweetmorn, Chaos 21, 3185 YOLD (discordian)
And let us not forget 13.0.6.3.2 by the Mayan Long Count

World History this day

1793 -- Louis XVI of France was guillotined
1925 -- Albania declared itself to be a republic.
1968 -- A B-52 crashed near Thule, contaminated the area with busted nukes and lost one nuke completely
2000 -- President Jamil Mahuad of Ecuador was deposed
2017 -- Over 400 US cities and 160+ countries hold a women's march,