21584787840 has 768 divisors, whose sum is σ = 95273418240. Its totient is φ = 4372070400.

The previous prime is 21584787803. The next prime is 21584787857. The reversal of 21584787840 is 4878748512.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 18183727 + ... + 18184913.

It is an arithmetic number, because the mean of its divisors is an integer number (124053930).

Almost surely, 2^21584787840 is an apocalyptic number.

21584787840 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 21584787840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (47636709120).

21584787840 is an abundant number, since it is smaller than the sum of its proper divisors (73688630400).

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

21584787840 is a wasteful number, since it uses less digits than its factorization.

21584787840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1271 (or 1256 counting only the distinct ones).

The product of its (nonzero) digits is 4014080, while the sum is 54.

The spelling of 21584787840 in words is "twenty-one billion, five hundred eighty-four million, seven hundred eighty-seven thousand, eight hundred forty".