81541785688 has 16 divisors (see below), whose sum is σ = 166790016360. Its totient is φ = 37064448000.

The previous prime is 81541785679. The next prime is 81541785691. The reversal of 81541785688 is 88658714518.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 463305513 + ... + 463305688.

Almost surely, 2^81541785688 is an apocalyptic number.

81541785688 is a gapful number since it is divisible by the number (88) formed by its first and last digit.

It is an amenable number.

81541785688 is an abundant number, since it is smaller than the sum of its proper divisors (85248230672).

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

81541785688 is a wasteful number, since it uses less digits than its factorization.

81541785688 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 926611218 (or 926611214 counting only the distinct ones).

The product of its digits is 17203200, while the sum is 61.

The spelling of 81541785688 in words is "eighty-one billion, five hundred forty-one million, seven hundred eighty-five thousand, six hundred eighty-eight".