81128007856 has 40 divisors (see below), whose sum is σ = 179660643840. Its totient is φ = 34765264704.

The previous prime is 81128007853. The next prime is 81128007899. The reversal of 81128007856 is 65870082118.

It is a hoax number, since the sum of its digits (46) 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 (81128007853) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1113705 + ... + 1184311.

It is an arithmetic number, because the mean of its divisors is an integer number (4491516096).

Almost surely, 2^81128007856 is an apocalyptic number.

It is an amenable number.

81128007856 is an abundant number, since it is smaller than the sum of its proper divisors (98532635984).

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

81128007856 is a wasteful number, since it uses less digits than its factorization.

81128007856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80881 (or 80875 counting only the distinct ones).

The product of its (nonzero) digits is 215040, while the sum is 46.

The spelling of 81128007856 in words is "eighty-one billion, one hundred twenty-eight million, seven thousand, eight hundred fifty-six".