18181923840 has 396 divisors, whose sum is σ = 66551024124. Its totient is φ = 4589125632.

The previous prime is 18181923833. The next prime is 18181923857. The reversal of 18181923840 is 4832918181.

18181923840 is a `hidden beast` number, since 1 + 8 + 181 + 92 + 384 + 0 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 13627293696 + 4554630144 = 116736^2 + 67488^2 .

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 16634334 + ... + 16635426.

Almost surely, 2^18181923840 is an apocalyptic number.

18181923840 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 18181923840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33275512062).

18181923840 is an abundant number, since it is smaller than the sum of its proper divisors (48369100284).

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

18181923840 is a wasteful number, since it uses less digits than its factorization.

18181923840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1162 (or 1122 counting only the distinct ones).

The product of its (nonzero) digits is 110592, while the sum is 45.

The spelling of 18181923840 in words is "eighteen billion, one hundred eighty-one million, nine hundred twenty-three thousand, eight hundred forty".