21509784000 has 672 divisors, whose sum is σ = 83077263360. Its totient is φ = 5296896000.

The previous prime is 21509783983. The next prime is 21509784011. The reversal of 21509784000 is 48790512.

It is a Harshad number since it is a multiple of its sum of digits (36).

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, 51335791 + ... + 51336209.

It is an arithmetic number, because the mean of its divisors is an integer number (123626880).

Almost surely, 2^21509784000 is an apocalyptic number.

21509784000 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 21509784000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41538631680).

21509784000 is an abundant number, since it is smaller than the sum of its proper divisors (61567479360).

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

21509784000 is a wasteful number, since it uses less digits than its factorization.

21509784000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 506 (or 483 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 36.

The spelling of 21509784000 in words is "twenty-one billion, five hundred nine million, seven hundred eighty-four thousand".