21981789930816 has 448 divisors, whose sum is σ = 68549943306240. Its totient is φ = 6893450403840.

The previous prime is 21981789930809. The next prime is 21981789930883. The reversal of 21981789930816 is 61803998718912.

It is a happy number.

21981789930816 is a `hidden beast` number, since 219 + 8 + 1 + 7 + 8 + 99 + 308 + 16 = 666.

It is a Harshad number since it is a multiple of its sum of digits (72).

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, 588311751 + ... + 588349113.

Almost surely, 2^{21981789930816} 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 21981789930816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34274971653120).

21981789930816 is an abundant number, since it is smaller than the sum of its proper divisors (46568153375424).

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

21981789930816 is a wasteful number, since it uses less digits than its factorization.

21981789930816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37651 (or 37635 counting only the distinct ones).

The product of its (nonzero) digits is 94058496, while the sum is 72.

The spelling of 21981789930816 in words is "twenty-one trillion, nine hundred eighty-one billion, seven hundred eighty-nine million, nine hundred thirty thousand, eight hundred sixteen".