The Russian Wikipedia has Mikhail's birth and death dates per the Gregorian calendar as 25Oct1820 - 22Jul1864. At the moment, the English Wikipedia is using 25Nov1820 - 22Jul1864. English Wikidata is listing Julian dates 13Oct1820 - 10Jul1864. It appears the English Wikipedia birth year of 25Nov1820 is perhaps wrong. So, currently using Russian Wikipedia Gregorian dates in this profile.