21009839616 has 200 divisors, whose sum is σ = 63218453760. Its totient is φ = 6946394112.

The previous prime is 21009839597. The next prime is 21009839639. The reversal of 21009839616 is 61693890012.

It is a happy number.

21009839616 is a `hidden beast` number, since 21 + 0 + 0 + 9 + 8 + 3 + 9 + 616 = 666.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 5264950 + ... + 5268938.

Almost surely, 2^21009839616 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21009839616, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31609226880).

21009839616 is an abundant number, since it is smaller than the sum of its proper divisors (42208614144).

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

21009839616 is an equidigital number, since it uses as much as digits as its factorization.

21009839616 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4146 (or 4121 counting only the distinct ones).

The product of its (nonzero) digits is 139968, while the sum is 45.

The spelling of 21009839616 in words is "twenty-one billion, nine million, eight hundred thirty-nine thousand, six hundred sixteen".