21593730816 has 432 divisors, whose sum is σ = 75124358400. Its totient is φ = 6099867648.

The previous prime is 21593730737. The next prime is 21593730817. The reversal of 21593730816 is 61803739512.

21593730816 is a `hidden beast` number, since 21 + 593 + 7 + 30 + 8 + 1 + 6 = 666.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21593730817) by changing a digit.

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, 34884555 + ... + 34885173.

Almost surely, 2^21593730816 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 21593730816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37562179200).

21593730816 is an abundant number, since it is smaller than the sum of its proper divisors (53530627584).

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

21593730816 is a wasteful number, since it uses less digits than its factorization.

21593730816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 761 (or 734 counting only the distinct ones).

The product of its (nonzero) digits is 272160, while the sum is 45.

It can be divided in two parts, 215937 and 30816, that added together give a triangular number (246753 = T₇₀₂).

The spelling of 21593730816 in words is "twenty-one billion, five hundred ninety-three million, seven hundred thirty thousand, eight hundred sixteen".