81128320 has 192 divisors, whose sum is σ = 244188000. Its totient is φ = 25546752.

The previous prime is 81128303. The next prime is 81128321. The reversal of 81128320 is 2382118.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81128321) 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 23 ways as a sum of consecutive naturals, for example, 407581 + ... + 407779.

Almost surely, 2^81128320 is an apocalyptic number.

81128320 is a gapful number since it is divisible by the number (80) 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 81128320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (122094000).

81128320 is an abundant number, since it is smaller than the sum of its proper divisors (163059680).

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

81128320 is a wasteful number, since it uses less digits than its factorization.

81128320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 245 (or 226 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 25.

The square root of 81128320 is about 9007.1260677310. The cubic root of 81128320 is about 432.9032313662.

The spelling of 81128320 in words is "eighty-one million, one hundred twenty-eight thousand, three hundred twenty".