18638913887 has 8 divisors (see below), whose sum is σ = 20530773120. Its totient is φ = 16779956760.

The previous prime is 18638913863. The next prime is 18638913893. The reversal of 18638913887 is 78831983681.

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

It is a cyclic number.

It is not a de Polignac number, because 18638913887 - 2²² = 18634719583 is a prime.

It is a super-2 number, since 2×18638913887² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18638913287) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8224337 + ... + 8226602.

It is an arithmetic number, because the mean of its divisors is an integer number (2566346640).

Almost surely, 2^18638913887 is an apocalyptic number.

18638913887 is a deficient number, since it is larger than the sum of its proper divisors (1891859233).

18638913887 is a wasteful number, since it uses less digits than its factorization.

18638913887 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16451053.

The product of its digits is 13934592, while the sum is 62.

The spelling of 18638913887 in words is "eighteen billion, six hundred thirty-eight million, nine hundred thirteen thousand, eight hundred eighty-seven".