21228328800 has 864 divisors, whose sum is σ = 92334090240. Its totient is φ = 4688409600.

The previous prime is 21228328799. The next prime is 21228328841. The reversal of 21228328800 is 882382212.

It is a tau number, because it is divible by the number of its divisors (864).

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

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 143 ways as a sum of consecutive naturals, for example, 32810077 + ... + 32810723.

It is an arithmetic number, because the mean of its divisors is an integer number (106868160).

Almost surely, 2^21228328800 is an apocalyptic number.

21228328800 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 21228328800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (46167045120).

21228328800 is an abundant number, since it is smaller than the sum of its proper divisors (71105761440).

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

21228328800 is a wasteful number, since it uses less digits than its factorization.

21228328800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 721 (or 695 counting only the distinct ones).

The product of its (nonzero) digits is 24576, while the sum is 36.

The spelling of 21228328800 in words is "twenty-one billion, two hundred twenty-eight million, three hundred twenty-eight thousand, eight hundred".