81328128 has 192 divisors, whose sum is σ = 259983360. Its totient is φ = 22118400.

The previous prime is 81328123. The next prime is 81328139. The reversal of 81328128 is 82182318.

It is a tau number, because it is divible by the number of its divisors (192).

It is a super-2 number, since 2×81328128² = 13228528807968768, which contains 22 as substring.

It is a nude number because it is divisible by every one of its digits and also a Zuckerman number because it is divisible by the product of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81328123) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1333218 + ... + 1333278.

It is an arithmetic number, because the mean of its divisors is an integer number (1354080).

Almost surely, 2^81328128 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 81328128, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (129991680).

81328128 is an abundant number, since it is smaller than the sum of its proper divisors (178655232).

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

81328128 is a wasteful number, since it uses less digits than its factorization.

81328128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 124 (or 104 counting only the distinct ones).

The product of its digits is 6144, while the sum is 33.

The square root of 81328128 is about 9018.2109090440. The cubic root of 81328128 is about 433.2583338972.

The spelling of 81328128 in words is "eighty-one million, three hundred twenty-eight thousand, one hundred twenty-eight".