18909073728 has 112 divisors (see below), whose sum is σ = 56638301760. Its totient is φ = 6184069632.

The previous prime is 18909073721. The next prime is 18909073747. The reversal of 18909073728 is 82737090981.

18909073728 is a `hidden beast` number, since 189 + 0 + 90 + 7 + 372 + 8 = 666.

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

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 (18909073721) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11650 + ... + 194817.

Almost surely, 2^18909073728 is an apocalyptic number.

18909073728 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 18909073728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28319150880).

18909073728 is an abundant number, since it is smaller than the sum of its proper divisors (37729228032).

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

18909073728 is a wasteful number, since it uses less digits than its factorization.

18909073728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 206541 (or 206525 counting only the distinct ones).

The product of its (nonzero) digits is 1524096, while the sum is 54.

The spelling of 18909073728 in words is "eighteen billion, nine hundred nine million, seventy-three thousand, seven hundred twenty-eight".