21897568 has 48 divisors (see below), whose sum is σ = 53754624. Its totient is φ = 8530560.

The previous prime is 21897559. The next prime is 21897569. The reversal of 21897568 is 86579812.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21897569) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1980 + ... + 6907.

It is an arithmetic number, because the mean of its divisors is an integer number (1119888).

Almost surely, 2^21897568 is an apocalyptic number.

21897568 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21897568 is an abundant number, since it is smaller than the sum of its proper divisors (31857056).

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

21897568 is a wasteful number, since it uses less digits than its factorization.

21897568 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8915 (or 8907 counting only the distinct ones).

The product of its digits is 241920, while the sum is 46.

The square root of 21897568 is about 4679.4837322081. The cubic root of 21897568 is about 279.7683798818.

The spelling of 21897568 in words is "twenty-one million, eight hundred ninety-seven thousand, five hundred sixty-eight".