81128541573 has 28 divisors (see below), whose sum is σ = 121943994508. Its totient is φ = 53949265920.

The previous prime is 81128541569. The next prime is 81128541589. The reversal of 81128541573 is 37514582118.

81128541573 is a `hidden beast` number, since 8 + 1 + 1 + 28 + 54 + 1 + 573 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 38699545284 + 42428996289 = 196722^2 + 205983^2 .

It is not a de Polignac number, because 81128541573 - 2² = 81128541569 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81128541553) by changing a digit.

It is a polite number, since it can be written in 27 ways as a sum of consecutive naturals, for example, 149253 + ... + 429573.

It is an arithmetic number, because the mean of its divisors is an integer number (4355142661).

Almost surely, 2^81128541573 is an apocalyptic number.

It is an amenable number.

81128541573 is a deficient number, since it is larger than the sum of its proper divisors (40815452935).

81128541573 is an equidigital number, since it uses as much as digits as its factorization.

81128541573 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 280736 (or 280721 counting only the distinct ones).

The product of its digits is 268800, while the sum is 45.

The spelling of 81128541573 in words is "eighty-one billion, one hundred twenty-eight million, five hundred forty-one thousand, five hundred seventy-three".