81688488618 has 16 divisors (see below), whose sum is σ = 178229429856. Its totient is φ = 24754087440.

The previous prime is 81688488569. The next prime is 81688488649.

81688488618 is nontrivially palindromic in base 10.

It is a Harshad number since it is a multiple of its sum of digits (66), and also a Moran number because the ratio is a prime number: 1237704373 = 81688488618 / (8 + 1 + 6 + 8 + 8 + 4 + 8 + 8 + 6 + 1 + 8).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 618852121 + ... + 618852252.

It is an arithmetic number, because the mean of its divisors is an integer number (11139339366).

Almost surely, 2^81688488618 is an apocalyptic number.

81688488618 is an abundant number, since it is smaller than the sum of its proper divisors (96540941238).

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

81688488618 is a wasteful number, since it uses less digits than its factorization.

81688488618 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1237704389.

The product of its digits is 37748736, while the sum is 66.

The spelling of 81688488618 in words is "eighty-one billion, six hundred eighty-eight million, four hundred eighty-eight thousand, six hundred eighteen".