21288928 has 12 divisors (see below), whose sum is σ = 41912640. Its totient is φ = 10644448.

The previous prime is 21288923. The next prime is 21288931. The reversal of 21288928 is 82988212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21288923) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332608 + ... + 332671.

It is an arithmetic number, because the mean of its divisors is an integer number (3492720).

Almost surely, 2^21288928 is an apocalyptic number.

It is an amenable number.

21288928 is a deficient number, since it is larger than the sum of its proper divisors (20623712).

21288928 is an equidigital number, since it uses as much as digits as its factorization.

21288928 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 665289 (or 665281 counting only the distinct ones).

The product of its digits is 36864, while the sum is 40.

The square root of 21288928 is about 4613.9926311168. The cubic root of 21288928 is about 277.1519452050.

The spelling of 21288928 in words is "twenty-one million, two hundred eighty-eight thousand, nine hundred twenty-eight".