21255175872 has 224 divisors, whose sum is σ = 71736752640. Its totient is φ = 6045373440.

The previous prime is 21255175867. The next prime is 21255175897. The reversal of 21255175872 is 27857155212.

21255175872 is a `hidden beast` number, since 2 + 1 + 2 + 55 + 17 + 587 + 2 = 666.

It is a tau number, because it is divible by the number of its divisors (224).

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 31 ways as a sum of consecutive naturals, for example, 2741922 + ... + 2749662.

It is an arithmetic number, because the mean of its divisors is an integer number (320253360).

Almost surely, 2^21255175872 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 21255175872, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35868376320).

21255175872 is an abundant number, since it is smaller than the sum of its proper divisors (50481576768).

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

21255175872 is a wasteful number, since it uses less digits than its factorization.

21255175872 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7996 (or 7980 counting only the distinct ones).

The product of its digits is 392000, while the sum is 45.

The spelling of 21255175872 in words is "twenty-one billion, two hundred fifty-five million, one hundred seventy-five thousand, eight hundred seventy-two".