81085284 has 72 divisors (see below), whose sum is σ = 237269760. Its totient is φ = 22868352.

The previous prime is 81085271. The next prime is 81085289. The reversal of 81085284 is 48258018.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (81085289) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 17872 + ... + 21944.

Almost surely, 2^81085284 is an apocalyptic number.

81085284 is a gapful number since it is divisible by the number (84) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81085284, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (118634880).

81085284 is an abundant number, since it is smaller than the sum of its proper divisors (156184476).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81085284 is a wasteful number, since it uses less digits than its factorization.

81085284 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4169 (or 4164 counting only the distinct ones).

The product of its (nonzero) digits is 20480, while the sum is 36.

The square root of 81085284 is about 9004.7367535092. The cubic root of 81085284 is about 432.8266706834.

The spelling of 81085284 in words is "eighty-one million, eighty-five thousand, two hundred eighty-four".