22 Apr 2222 = [2221 years + period from 1-Jan-2222 to 22-Apr-2222]

We know that number of odd days in 400 years = 0

Hence the number of odd days in 2000 years = 0 [Since 2000 is a perfect multiple of 400]

Number of odd days in the period 2001-2200

= Number of odd days in 200 years

= 5 x 2 = 10 = 3

As we can reduce perfect multiples of 7 from odd days without affecting anything

Number of odd days in the period 2201-2221

= 16 normal years + 5 leap years

= 16 x 1 + 5 x 2 = 16 + 10 = 26 = 5 odd days

Number of days from 1-Jan-2222 to 22 Apr 2222

= 31 Jan + 28 Feb + 31 Mar + 22Apr = 112

112 days = 0 odd day

Total number of odd days = 0 + 3 + 5 + 0 = 8 = 1 odd day

1 odd days = Monday

Hence 22 Apr 2222 is Monday.