81427728 has 40 divisors (see below), whose sum is σ = 219503808. Its totient is φ = 25962112.

The previous prime is 81427721. The next prime is 81427747. The reversal of 81427728 is 82772418.

It is a hoax number, since the sum of its digits (39) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (81427721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 35775 + ... + 37982.

Almost surely, 2^81427728 is an apocalyptic number.

It is an amenable number.

81427728 is an abundant number, since it is smaller than the sum of its proper divisors (138076080).

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

81427728 is a wasteful number, since it uses less digits than its factorization.

81427728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73791 (or 73785 counting only the distinct ones).

The product of its digits is 50176, while the sum is 39.

The square root of 81427728 is about 9023.7313789806. The cubic root of 81427728 is about 433.4351276964.

The spelling of 81427728 in words is "eighty-one million, four hundred twenty-seven thousand, seven hundred twenty-eight".