81681588492 has 48 divisors (see below), whose sum is σ = 220441896192. Its totient is φ = 23056418880.

The previous prime is 81681588479. The next prime is 81681588497. The reversal of 81681588492 is 29488518618.

It is not an unprimeable number, because it can be changed into a prime (81681588497) 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, 5850859 + ... + 5864802.

It is an arithmetic number, because the mean of its divisors is an integer number (4592539504).

Almost surely, 2^81681588492 is an apocalyptic number.

It is an amenable number.

81681588492 is an abundant number, since it is smaller than the sum of its proper divisors (138760307700).

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

81681588492 is a wasteful number, since it uses less digits than its factorization.

81681588492 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11715758 (or 11715756 counting only the distinct ones).

The product of its digits is 8847360, while the sum is 60.

The spelling of 81681588492 in words is "eighty-one billion, six hundred eighty-one million, five hundred eighty-eight thousand, four hundred ninety-two".