21055686912 has 360 divisors, whose sum is σ = 71189740160. Its totient is φ = 6136197120.

The previous prime is 21055686833. The next prime is 21055686913. The reversal of 21055686912 is 21968655012.

21055686912 is a `hidden beast` number, since 2 + 1 + 0 + 556 + 8 + 6 + 91 + 2 = 666.

It is not an unprimeable number, because it can be changed into a prime (21055686913) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 5119737 + ... + 5123847.

Almost surely, 2^21055686912 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21055686912, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35594870080).

21055686912 is an abundant number, since it is smaller than the sum of its proper divisors (50134053248).

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

21055686912 is a wasteful number, since it uses less digits than its factorization.

21055686912 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4171 (or 4148 counting only the distinct ones).

The product of its (nonzero) digits is 259200, while the sum is 45.

The spelling of 21055686912 in words is "twenty-one billion, fifty-five million, six hundred eighty-six thousand, nine hundred twelve".