21981798396 has 18 divisors (see below), whose sum is σ = 55565101592. Its totient is φ = 7327266120.

The previous prime is 21981798379. The next prime is 21981798407. The reversal of 21981798396 is 69389718912.

It is a tau number, because it is divible by the number of its divisors (18).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 305302720 + ... + 305302791.

Almost surely, 2^21981798396 is an apocalyptic number.

It is an amenable number.

21981798396 is an abundant number, since it is smaller than the sum of its proper divisors (33583303196).

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

21981798396 is a wasteful number, since it uses less digits than its factorization.

21981798396 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 610605521 (or 610605516 counting only the distinct ones).

The product of its digits is 11757312, while the sum is 63.

The spelling of 21981798396 in words is "twenty-one billion, nine hundred eighty-one million, seven hundred ninety-eight thousand, three hundred ninety-six".