21380928 has 56 divisors (see below), whose sum is σ = 59557920. Its totient is φ = 6750720.

The previous prime is 21380923. The next prime is 21380929. The reversal of 21380928 is 82908312.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21380921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 718 + ... + 6578.

Almost surely, 2^21380928 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 21380928, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29778960).

21380928 is an abundant number, since it is smaller than the sum of its proper divisors (38176992).

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

21380928 is a wasteful number, since it uses less digits than its factorization.

21380928 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5895 (or 5885 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 33.

The square root of 21380928 is about 4623.9515568397. The cubic root of 21380928 is about 277.5506084145.

The spelling of 21380928 in words is "twenty-one million, three hundred eighty thousand, nine hundred twenty-eight".