18721686687 has 32 divisors (see below), whose sum is σ = 29079336960. Its totient is φ = 10601808000.

The previous prime is 18721686649. The next prime is 18721686701. The reversal of 18721686687 is 78668612781.

It is a happy number.

It is not a de Polignac number, because 18721686687 - 2¹⁸ = 18721424543 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 18721686687.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18721686187) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 285864 + ... + 345197.

It is an arithmetic number, because the mean of its divisors is an integer number (908729280).

Almost surely, 2^18721686687 is an apocalyptic number.

18721686687 is a deficient number, since it is larger than the sum of its proper divisors (10357650273).

18721686687 is a wasteful number, since it uses less digits than its factorization.

18721686687 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 631135.

The product of its digits is 10838016, while the sum is 60.

The spelling of 18721686687 in words is "eighteen billion, seven hundred twenty-one million, six hundred eighty-six thousand, six hundred eighty-seven".