81823728 has 120 divisors (see below), whose sum is σ = 258971520. Its totient is φ = 22135680.

The previous prime is 81823727. The next prime is 81823759. The reversal of 81823728 is 82732818.

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81823727) 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, 43773 + ... + 45603.

It is an arithmetic number, because the mean of its divisors is an integer number (2158096).

Almost surely, 2^81823728 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81823728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (129485760).

81823728 is an abundant number, since it is smaller than the sum of its proper divisors (177147792).

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

81823728 is a wasteful number, since it uses less digits than its factorization.

81823728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1875 (or 1862 counting only the distinct ones).

The product of its digits is 43008, while the sum is 39.

The square root of 81823728 is about 9045.6469088728. The cubic root of 81823728 is about 434.1366201865.

The spelling of 81823728 in words is "eighty-one million, eight hundred twenty-three thousand, seven hundred twenty-eight".