No. Numbers in a normal sentence are not capitalized.
Example: "My birthday is on the twentieth of January."
January twentieth
Twentieth, which is the way you have it, is the correct spelling, as in the 20th of January.
January 1, 1951
The 80s was in the twentieth century. The twentieth century began in 1900 and ended on January 1, 2000 which marked the beginning of a new millennium.
Zodiac signs for January include the Capricorn which is from January the first to January the nineteenth. And also the Aquarius which is from January twentieth to January thirty-first.
January 23, 1933 was the date the 20th was ratified/
on the twentieth day of January following their election
The Twentieth Century - 1957 Crisis at Suez 5-13 was released on: USA: 28 January 1962
The Twentieth Century - 1957 Siege at Malta 5-10 was released on: USA: 7 January 1962
The Twentieth Century - 1957 Korea the Line 8-6 was released on: USA: 24 January 1965
The Twentieth Century - 1957 Invasion of Sicily 7-12 was released on: USA: 19 January 1964
The Twentieth Century - 1957 The Week That Shook the World - 3.11 was released on: USA: 10 January 1960