21565870748928 has 432 divisors, whose sum is σ = 70926369713472. Its totient is φ = 6535087257600.

The previous prime is 21565870748909. The next prime is 21565870748953. The reversal of 21565870748928 is 82984707856512.

21565870748928 is a `hidden beast` number, since 2 + 1 + 5 + 6 + 58 + 70 + 7 + 489 + 28 = 666.

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

It is a super-2 number, since 2×21565870748928² (a number of 27 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (72).

It is a congruent number.

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 47 ways as a sum of consecutive naturals, for example, 82668618 + ... + 82929078.

Almost surely, 2^{21565870748928} 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 21565870748928, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35463184856736).

21565870748928 is an abundant number, since it is smaller than the sum of its proper divisors (49360498964544).

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

21565870748928 is an frugal number, since it uses more digits than its factorization.

21565870748928 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 260525 (or 260477 counting only the distinct ones).

The product of its (nonzero) digits is 541900800, while the sum is 72.

The spelling of 21565870748928 in words is "twenty-one trillion, five hundred sixty-five billion, eight hundred seventy million, seven hundred forty-eight thousand, nine hundred twenty-eight".