28280021 has 8 divisors (see below), whose sum is σ = 35258304. Its totient is φ = 22036320.

The previous prime is 28279997. The next prime is 28280047. The reversal of 28280021 is 12008282.

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

It is a cyclic number.

It is not a de Polignac number, because 28280021 - 2²² = 24085717 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28280621) 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, 183560 + ... + 183713.

It is an arithmetic number, because the mean of its divisors is an integer number (4407288).

Almost surely, 2^28280021 is an apocalyptic number.

It is an amenable number.

28280021 is a deficient number, since it is larger than the sum of its proper divisors (6978283).

28280021 is a wasteful number, since it uses less digits than its factorization.

28280021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 367291.

The product of its (nonzero) digits is 512, while the sum is 23.

The square root of 28280021 is about 5317.8962945887. The cubic root of 28280021 is about 304.6678135569.

The spelling of 28280021 in words is "twenty-eight million, two hundred eighty thousand, twenty-one".