18038978640 has 240 divisors, whose sum is σ = 63058963968. Its totient is φ = 4792462848.

The previous prime is 18038978623. The next prime is 18038978641. The reversal of 18038978640 is 4687983081.

18038978640 is a `hidden beast` number, since 180 + 389 + 7 + 86 + 4 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (240).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18038978641) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 5694337 + ... + 5697503.

Almost surely, 2^18038978640 is an apocalyptic number.

18038978640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18038978640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31529481984).

18038978640 is an abundant number, since it is smaller than the sum of its proper divisors (45019985328).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

18038978640 is a wasteful number, since it uses less digits than its factorization.

18038978640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3488 (or 3470 counting only the distinct ones).

The product of its (nonzero) digits is 2322432, while the sum is 54.

The spelling of 18038978640 in words is "eighteen billion, thirty-eight million, nine hundred seventy-eight thousand, six hundred forty".