21564244560 has 320 divisors, whose sum is σ = 73281024000. Its totient is φ = 5224826880.

The previous prime is 21564244553. The next prime is 21564244621. The reversal of 21564244560 is 6544246512.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 23670505 + ... + 23671415.

It is an arithmetic number, because the mean of its divisors is an integer number (229003200).

Almost surely, 2^21564244560 is an apocalyptic number.

21564244560 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 21564244560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36640512000).

21564244560 is an abundant number, since it is smaller than the sum of its proper divisors (51716779440).

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

21564244560 is a wasteful number, since it uses less digits than its factorization.

21564244560 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1154 (or 1148 counting only the distinct ones).

The product of its (nonzero) digits is 230400, while the sum is 39.

The spelling of 21564244560 in words is "twenty-one billion, five hundred sixty-four million, two hundred forty-four thousand, five hundred sixty".