21572812800 has 1224 divisors, whose sum is σ = 101417496960. Its totient is φ = 4246732800.

The previous prime is 21572812787. The next prime is 21572812801. The reversal of 21572812800 is 821827512.

21572812800 is a `hidden beast` number, since 2 + 1 + 572 + 8 + 1 + 2 + 80 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21572812801) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 1135411191 + ... + 1135411209.

Almost surely, 2^21572812800 is an apocalyptic number.

21572812800 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21572812800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (50708748480).

21572812800 is an abundant number, since it is smaller than the sum of its proper divisors (79844684160).

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

21572812800 is a wasteful number, since it uses less digits than its factorization.

21572812800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 85 (or 47 counting only the distinct ones).

The product of its (nonzero) digits is 17920, while the sum is 36.

It can be divided in two parts, 2157281 and 2800, that added together give a triangular number (2160081 = T₂₀₇₈).

The spelling of 21572812800 in words is "twenty-one billion, five hundred seventy-two million, eight hundred twelve thousand, eight hundred".