21568893840 has 720 divisors, whose sum is σ = 84565681200. Its totient is φ = 5079158784.

The previous prime is 21568893817. The next prime is 21568893847. The reversal of 21568893840 is 4839886512.

21568893840 is a `hidden beast` number, since 2 + 1 + 568 + 8 + 9 + 38 + 40 = 666.

It can be written as a sum of positive squares in 8 ways, for example, as 499790736 + 21069103104 = 22356^2 + 145152^2 .

It is a tau number, because it is divible by the number of its divisors (720).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is not an unprimeable number, because it can be changed into a prime (21568893847) by changing a digit.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 197879706 + ... + 197879814.

It is an arithmetic number, because the mean of its divisors is an integer number (117452335).

Almost surely, 2^21568893840 is an apocalyptic number.

21568893840 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 21568893840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (42282840600).

21568893840 is an abundant number, since it is smaller than the sum of its proper divisors (62996787360).

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

21568893840 is a wasteful number, since it uses less digits than its factorization.

21568893840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 188 (or 161 counting only the distinct ones).

The product of its (nonzero) digits is 3317760, while the sum is 54.

The spelling of 21568893840 in words is "twenty-one billion, five hundred sixty-eight million, eight hundred ninety-three thousand, eight hundred forty".