28820921 has 8 divisors (see below), whose sum is σ = 29457600. Its totient is φ = 28190448.

The previous prime is 28820893. The next prime is 28820927. The reversal of 28820921 is 12902882.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28820921 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28820927) 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, 8540 + ... + 11426.

It is an arithmetic number, because the mean of its divisors is an integer number (3682200).

Almost surely, 2^28820921 is an apocalyptic number.

It is an amenable number.

28820921 is a deficient number, since it is larger than the sum of its proper divisors (636679).

28820921 is a wasteful number, since it uses less digits than its factorization.

28820921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3103.

The product of its (nonzero) digits is 4608, while the sum is 32.

The square root of 28820921 is about 5368.5119912318. The cubic root of 28820921 is about 306.5979770278.

The spelling of 28820921 in words is "twenty-eight million, eight hundred twenty thousand, nine hundred twenty-one".