'Twenty first' in the Bible

In the first month, on the fourteenth day of the month at evening, you shall eat unleavened bread, until the twenty-first day of the month at evening.

the twenty-first for Jachin, the twenty-second for Gamul,

for the twenty-first to Hothir, his sons and his relatives, twelve;

On the twenty-first of the seventh month, the word of the Lord came by Haggai the prophet saying,