18861638400 has 432 divisors, whose sum is σ = 75458920320. Its totient is φ = 4572057600.

The previous prime is 18861638387. The next prime is 18861638423. The reversal of 18861638400 is 483616881.

It is a happy number.

18861638400 is a `hidden beast` number, since 1 + 8 + 8 + 6 + 1 + 638 + 4 + 0 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (432).

It is a super-3 number, since 3×18861638400³ (a number of 32 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

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

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 47 ways as a sum of consecutive naturals, for example, 1895839 + ... + 1905761.

Almost surely, 2^18861638400 is an apocalyptic number.

18861638400 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 18861638400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37729460160).

18861638400 is an abundant number, since it is smaller than the sum of its proper divisors (56597281920).

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

18861638400 is a wasteful number, since it uses less digits than its factorization.

18861638400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9969 (or 9944 counting only the distinct ones).

The product of its (nonzero) digits is 221184, while the sum is 45.

The spelling of 18861638400 in words is "eighteen billion, eight hundred sixty-one million, six hundred thirty-eight thousand, four hundred".