21609825728 has 28 divisors (see below), whose sum is σ = 44040975672. Its totient is φ = 10512887040.

The previous prime is 21609825709. The next prime is 21609825739. The reversal of 21609825728 is 82752890612.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4560518 + ... + 4565253.

Almost surely, 2^21609825728 is an apocalyptic number.

It is an amenable number.

21609825728 is an abundant number, since it is smaller than the sum of its proper divisors (22431149944).

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

21609825728 is an equidigital number, since it uses as much as digits as its factorization.

21609825728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9125820 (or 9125810 counting only the distinct ones).

The product of its (nonzero) digits is 967680, while the sum is 50.

The spelling of 21609825728 in words is "twenty-one billion, six hundred nine million, eight hundred twenty-five thousand, seven hundred twenty-eight".