81548539638 has 32 divisors (see below), whose sum is σ = 175673731200. Its totient is φ = 25153281216.

The previous prime is 81548539637. The next prime is 81548539649. The reversal of 81548539638 is 83693584518.

It is a super-3 number, since 3×81548539638³ (a number of 34 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81548539637) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8312983 + ... + 8322786.

It is an arithmetic number, because the mean of its divisors is an integer number (5489804100).

Almost surely, 2^81548539638 is an apocalyptic number.

81548539638 is an abundant number, since it is smaller than the sum of its proper divisors (94125191562).

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

81548539638 is a wasteful number, since it uses less digits than its factorization.

81548539638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16635836.

The product of its digits is 24883200, while the sum is 60.

The spelling of 81548539638 in words is "eighty-one billion, five hundred forty-eight million, five hundred thirty-nine thousand, six hundred thirty-eight".