21685708800 has 1008 divisors, whose sum is σ = 93240594720. Its totient is φ = 4897013760.

The previous prime is 21685708771. The next prime is 21685708817. The reversal of 21685708800 is 880758612.

It is a tau number, because it is divible by the number of its divisors (1008).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 83 ways as a sum of consecutive naturals, for example, 261273559 + ... + 261273641.

It is an arithmetic number, because the mean of its divisors is an integer number (92500590).

Almost surely, 2^21685708800 is an apocalyptic number.

21685708800 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 21685708800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (46620297360).

21685708800 is an abundant number, since it is smaller than the sum of its proper divisors (71554885920).

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

21685708800 is an frugal number, since it uses more digits than its factorization.

21685708800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 140 (or 100 counting only the distinct ones).

The product of its (nonzero) digits is 215040, while the sum is 45.

The spelling of 21685708800 in words is "twenty-one billion, six hundred eighty-five million, seven hundred eight thousand, eight hundred".