18855640728 has 80 divisors (see below), whose sum is σ = 52865505000. Its totient is φ = 6278995584.

The previous prime is 18855640721. The next prime is 18855640733. The reversal of 18855640728 is 82704655881.

18855640728 is a `hidden beast` number, since 1 + 8 + 8 + 5 + 564 + 0 + 72 + 8 = 666.

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 (18855640721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 665883 + ... + 693621.

Almost surely, 2^18855640728 is an apocalyptic number.

18855640728 is a gapful number since it is divisible by the number (18) 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 18855640728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26432752500).

18855640728 is an abundant number, since it is smaller than the sum of its proper divisors (34009864272).

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

18855640728 is a wasteful number, since it uses less digits than its factorization.

18855640728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28806 (or 28793 counting only the distinct ones).

The product of its (nonzero) digits is 4300800, while the sum is 54.

The spelling of 18855640728 in words is "eighteen billion, eight hundred fifty-five million, six hundred forty thousand, seven hundred twenty-eight".