81687478618 has 8 divisors (see below), whose sum is σ = 123071003712. Its totient is φ = 40663810716.

The previous prime is 81687478597. The next prime is 81687478657.

81687478618 is nontrivially palindromic in base 10.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a self number, because there is not a number n which added to its sum of digits gives 81687478618.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 89963730 + ... + 89964637.

It is an arithmetic number, because the mean of its divisors is an integer number (15383875464).

Almost surely, 2^81687478618 is an apocalyptic number.

81687478618 is a deficient number, since it is larger than the sum of its proper divisors (41383525094).

81687478618 is a wasteful number, since it uses less digits than its factorization.

81687478618 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 179928596.

The product of its digits is 28901376, while the sum is 64.

The spelling of 81687478618 in words is "eighty-one billion, six hundred eighty-seven million, four hundred seventy-eight thousand, six hundred eighteen".