21931443072 has 384 divisors, whose sum is σ = 79002443520. Its totient is φ = 5673369600.

The previous prime is 21931443041. The next prime is 21931443077. The reversal of 21931443072 is 27034413912.

It is a happy number.

21931443072 is a `hidden beast` number, since 219 + 3 + 1 + 4 + 430 + 7 + 2 = 666.

It is a tau number, because it is divible by the number of its divisors (384).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21931443077) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 38408547 + ... + 38409117.

It is an arithmetic number, because the mean of its divisors is an integer number (205735530).

Almost surely, 2^21931443072 is an apocalyptic number.

21931443072 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21931443072, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39501221760).

21931443072 is an abundant number, since it is smaller than the sum of its proper divisors (57071000448).

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

21931443072 is a wasteful number, since it uses less digits than its factorization.

21931443072 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1042 (or 1027 counting only the distinct ones).

The product of its (nonzero) digits is 36288, while the sum is 36.

Adding to 21931443072 its reverse (27034413912), we get a palindrome (48965856984).

The spelling of 21931443072 in words is "twenty-one billion, nine hundred thirty-one million, four hundred forty-three thousand, seventy-two".