21979626816 has 448 divisors, whose sum is σ = 73657886720. Its totient is φ = 5643509760.

The previous prime is 21979626803. The next prime is 21979626821. The reversal of 21979626816 is 61862697912.

It is a tau number, because it is divible by the number of its divisors (448).

It is a Harshad number since it is a multiple of its sum of digits (57).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 40627506 + ... + 40628046.

Almost surely, 2^21979626816 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 21979626816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36828943360).

21979626816 is an abundant number, since it is smaller than the sum of its proper divisors (51678259904).

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

21979626816 is a wasteful number, since it uses less digits than its factorization.

21979626816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 662 (or 652 counting only the distinct ones).

The product of its digits is 3919104, while the sum is 57.

The spelling of 21979626816 in words is "twenty-one billion, nine hundred seventy-nine million, six hundred twenty-six thousand, eight hundred sixteen".