i) Sum of digits in 19725462 is 36, which is divisible by 9.
So, the given number is divisible by 9.
ii) Sum of digits in 36870521 is 32, which is not divisible by 9.
So, the given number is not divisible by 9.

i) The number formed by the last 2 digits in the given number is 94, which is not divisible by 4
`:.` 67920594 is not divisible by 4.
ii) The number formed by the last 2 digits in the given number is 72, which is not divisible by 4
`:.` 618703572 is divisible by 4.

i) The number formed by the last 3 digits of the given number is 542, which is not divisible by 8.
`:.` 98016542 is not divisible by 8.
ii) The number formed by the last 3 digits of the given number is 304, which is not divisible by 8.
`:.` 106598304 is divisible by 8.

(Sum of digits at odd places) - (Sum of digits at even places)
=[(8 + 7 + 3 + 4) - (1 + 2 + 8)]=11, which is divisible by 11.
`:.` 4832718 is divisible by 11.

No, since 6 and 4 are not co-prime.
36 is divisible by 6 as well as 4 but it is not divisible by 24.