28365021 has 6 divisors (see below), whose sum is σ = 40971710. Its totient is φ = 18910008.

The previous prime is 28365019. The next prime is 28365023. The reversal of 28365021 is 12056382.

28365021 is a `hidden beast` number, since 2 + 8 + 3 + 650 + 2 + 1 = 666.

It is an interprime number because it is at equal distance from previous prime (28365019) and next prime (28365023).

It can be written as a sum of positive squares in only one way, i.e., 28196100 + 168921 = 5310^2 + 411^2 .

It is not a de Polignac number, because 28365021 - 2¹ = 28365019 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28365023) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1575826 + ... + 1575843.

Almost surely, 2^28365021 is an apocalyptic number.

It is an amenable number.

28365021 is a deficient number, since it is larger than the sum of its proper divisors (12606689).

28365021 is a wasteful number, since it uses less digits than its factorization.

28365021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3151675 (or 3151672 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 27.

The square root of 28365021 is about 5325.8821804467. The cubic root of 28365021 is about 304.9727504097.

The spelling of 28365021 in words is "twenty-eight million, three hundred sixty-five thousand, twenty-one".