Republic Day of India was celebrated on Thursday in 2017. On which day it was celebrated in 2021?

Tuesday

We know that in 365 days we have 1 odd day.
26 January 2017 = Thursday
26 January 2018 = Friday
26 January 2019 = Saturday
26 January 2020 = Sunday.

2020 is a leap year so February has 29 days.
26 January 2021 = Sunday + 2 = Tuesday (+2 because of leap year, In 366 days we have 2 odd days)