Given, number is 61479.

Need to find out the number is divisible by 81

⇒ Prime factors of 81 = 9 × 9

∴ it is enough to find the number is divisible by 9

⇒ To test the number is divisible by 9 it can be found by summing of the digits

⇒ 6 + 1 + 4 + 7 + 9 = 27

∴ number 27 is divisible by 9

Hence, 61479 is divisible by 81.