21791128 has 16 divisors (see below), whose sum is σ = 41017680. Its totient is φ = 10853088.

The previous prime is 21791117. The next prime is 21791137. The reversal of 21791128 is 82119712.

It is a self number, because there is not a number n which added to its sum of digits gives 21791128.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3075 + ... + 7282.

It is an arithmetic number, because the mean of its divisors is an integer number (2563605).

Almost surely, 2^21791128 is an apocalyptic number.

It is an amenable number.

21791128 is a deficient number, since it is larger than the sum of its proper divisors (19226552).

21791128 is a wasteful number, since it uses less digits than its factorization.

21791128 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10626 (or 10622 counting only the distinct ones).

The product of its digits is 2016, while the sum is 31.

The square root of 21791128 is about 4668.0968284730. The cubic root of 21791128 is about 279.3143427578.

The spelling of 21791128 in words is "twenty-one million, seven hundred ninety-one thousand, one hundred twenty-eight".