81432138591 has 48 divisors (see below), whose sum is σ = 125173152000. Its totient is φ = 52319842848.

The previous prime is 81432138577. The next prime is 81432138631. The reversal of 81432138591 is 19583123418.

81432138591 is a `hidden beast` number, since 8 + 1 + 4 + 3 + 21 + 38 + 591 = 666.

It is not a de Polignac number, because 81432138591 - 2¹³ = 81432130399 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81432138511) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 13598500 + ... + 13604486.

It is an arithmetic number, because the mean of its divisors is an integer number (2607774000).

Almost surely, 2^81432138591 is an apocalyptic number.

81432138591 is a deficient number, since it is larger than the sum of its proper divisors (43741013409).

81432138591 is a wasteful number, since it uses less digits than its factorization.

81432138591 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6653 (or 6618 counting only the distinct ones).

The product of its digits is 207360, while the sum is 45.

The spelling of 81432138591 in words is "eighty-one billion, four hundred thirty-two million, one hundred thirty-eight thousand, five hundred ninety-one".