28867021 has 4 divisors (see below), whose sum is σ = 28892412. Its totient is φ = 28841632.

The previous prime is 28867019. The next prime is 28867031. The reversal of 28867021 is 12076882.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12076882 = 2 ⋅6038441.

It can be written as a sum of positive squares in 2 ways, for example, as 10634121 + 18232900 = 3261^2 + 4270^2 .

It is a cyclic number.

It is not a de Polignac number, because 28867021 - 2¹ = 28867019 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 (28867031) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10906 + ... + 13291.

It is an arithmetic number, because the mean of its divisors is an integer number (7223103).

Almost surely, 2^28867021 is an apocalyptic number.

It is an amenable number.

28867021 is a deficient number, since it is larger than the sum of its proper divisors (25391).

28867021 is a wasteful number, since it uses less digits than its factorization.

28867021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25390.

The product of its (nonzero) digits is 10752, while the sum is 34.

The square root of 28867021 is about 5372.8038304036. The cubic root of 28867021 is about 306.7613610896.

The spelling of 28867021 in words is "twenty-eight million, eight hundred sixty-seven thousand, twenty-one".