18909813638 has 8 divisors (see below), whose sum is σ = 28365553632. Its totient is φ = 9454629096.

The previous prime is 18909813623. The next prime is 18909813673. The reversal of 18909813638 is 83631890981.

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

It is a congruent number.

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, 39545 + ... + 198452.

It is an arithmetic number, because the mean of its divisors is an integer number (3545694204).

Almost surely, 2^18909813638 is an apocalyptic number.

18909813638 is a deficient number, since it is larger than the sum of its proper divisors (9455739994).

18909813638 is a wasteful number, since it uses less digits than its factorization.

18909813638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 277726.

The product of its (nonzero) digits is 2239488, while the sum is 56.

The spelling of 18909813638 in words is "eighteen billion, nine hundred nine million, eight hundred thirteen thousand, six hundred thirty-eight".