18865861920 has 288 divisors, whose sum is σ = 66387707568. Its totient is φ = 4875116544.

The previous prime is 18865861913. The next prime is 18865861967. The reversal of 18865861920 is 2916856881.

It is a happy number.

18865861920 is a `hidden beast` number, since 18 + 8 + 6 + 5 + 8 + 619 + 2 + 0 = 666.

It can be written as a sum of positive squares in 8 ways, for example, as 2621849616 + 16244012304 = 51204^2 + 127452^2 .

It is a tau number, because it is divible by the number of its divisors (288).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 16889202 + ... + 16890318.

Almost surely, 2^18865861920 is an apocalyptic number.

18865861920 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 18865861920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33193853784).

18865861920 is an abundant number, since it is smaller than the sum of its proper divisors (47521845648).

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

18865861920 is a wasteful number, since it uses less digits than its factorization.

18865861920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1492 (or 1481 counting only the distinct ones).

The product of its (nonzero) digits is 1658880, while the sum is 54.

The spelling of 18865861920 in words is "eighteen billion, eight hundred sixty-five million, eight hundred sixty-one thousand, nine hundred twenty".