81128880 has 120 divisors (see below), whose sum is σ = 311399712. Its totient is φ = 18542592.

The previous prime is 81128857. The next prime is 81128897. The reversal of 81128880 is 8882118.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (120).

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

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3009 + ... + 13088.

Almost surely, 2^81128880 is an apocalyptic number.

81128880 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 81128880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (155699856).

81128880 is an abundant number, since it is smaller than the sum of its proper divisors (230270832).

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

81128880 is a wasteful number, since it uses less digits than its factorization.

81128880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16123 (or 16114 counting only the distinct ones).

The product of its (nonzero) digits is 8192, while the sum is 36.

The square root of 81128880 is about 9007.1571541747. The cubic root of 81128880 is about 432.9042274230.

The spelling of 81128880 in words is "eighty-one million, one hundred twenty-eight thousand, eight hundred eighty".