21157638912 has 144 divisors (see below), whose sum is σ = 65287649280. Its totient is φ = 6745863168.

The previous prime is 21157638907. The next prime is 21157639003. The reversal of 21157638912 is 21983675112.

21157638912 is a `hidden beast` number, since 2 + 1 + 1 + 5 + 7 + 638 + 9 + 1 + 2 = 666.

It is a tau number, because it is divible by the number of its divisors (144).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 92433 + ... + 225519.

Almost surely, 2^21157638912 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 21157638912, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32643824640).

21157638912 is an abundant number, since it is smaller than the sum of its proper divisors (44130010368).

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

21157638912 is a wasteful number, since it uses less digits than its factorization.

21157638912 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 133135 (or 133115 counting only the distinct ones).

The product of its digits is 181440, while the sum is 45.

The spelling of 21157638912 in words is "twenty-one billion, one hundred fifty-seven million, six hundred thirty-eight thousand, nine hundred twelve".