21609728784000 has 768 divisors, whose sum is σ = 88784581017600. Its totient is φ = 4934239027200.

The previous prime is 21609728783971. The next prime is 21609728784031. The reversal of 21609728784000 is 48782790612.

It is a happy number.

21609728784000 is a `hidden beast` number, since 2 + 1 + 60 + 97 + 28 + 78 + 400 + 0 = 666.

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, 1017061377 + ... + 1017082623.

It is an arithmetic number, because the mean of its divisors is an integer number (115604923200).

Almost surely, 2^{21609728784000} is an apocalyptic number.

21609728784000 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 21609728784000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (44392290508800).

21609728784000 is an abundant number, since it is smaller than the sum of its proper divisors (67174852233600).

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

21609728784000 is a wasteful number, since it uses less digits than its factorization.

21609728784000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22298 (or 22273 counting only the distinct ones).

The product of its (nonzero) digits is 2709504, while the sum is 54.

The spelling of 21609728784000 in words is "twenty-one trillion, six hundred nine billion, seven hundred twenty-eight million, seven hundred eighty-four thousand".