18715720387 has 32 divisors (see below), whose sum is σ = 23567667200. Its totient is φ = 14469331968.

The previous prime is 18715720367. The next prime is 18715720391. The reversal of 18715720387 is 78302751781.

It is a de Polignac number, because none of the positive numbers 2^k-18715720387 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 18715720387.

It is not an unprimeable number, because it can be changed into a prime (18715720327) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 683914 + ... + 710752.

It is an arithmetic number, because the mean of its divisors is an integer number (736489600).

Almost surely, 2^18715720387 is an apocalyptic number.

18715720387 is a deficient number, since it is larger than the sum of its proper divisors (4851946813).

18715720387 is a wasteful number, since it uses less digits than its factorization.

18715720387 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27035.

The product of its (nonzero) digits is 658560, while the sum is 49.

The spelling of 18715720387 in words is "eighteen billion, seven hundred fifteen million, seven hundred twenty thousand, three hundred eighty-seven".