20921506800 has 240 divisors, whose sum is σ = 68269440000. Its totient is φ = 5475824640.

The previous prime is 20921506799. The next prime is 20921506843. The reversal of 20921506800 is 860512902.

It is a tau number, because it is divible by the number of its divisors (240).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 18864646 + ... + 18865754.

It is an arithmetic number, because the mean of its divisors is an integer number (284456000).

Almost surely, 2^20921506800 is an apocalyptic number.

20921506800 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 20921506800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34134720000).

20921506800 is an abundant number, since it is smaller than the sum of its proper divisors (47347933200).

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

20921506800 is a wasteful number, since it uses less digits than its factorization.

20921506800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1408 (or 1397 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 33.

The spelling of 20921506800 in words is "twenty billion, nine hundred twenty-one million, five hundred six thousand, eight hundred".