28284021 has 24 divisors (see below), whose sum is σ = 42304184. Its totient is φ = 18195840.

The previous prime is 28283987. The next prime is 28284023. The reversal of 28284021 is 12048282.

It can be written as a sum of positive squares in 4 ways, for example, as 5616900 + 22667121 = 2370^2 + 4761^2 .

It is not a de Polignac number, because 28284021 - 2⁹ = 28283509 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 (28284023) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 52011 + ... + 52551.

Almost surely, 2^28284021 is an apocalyptic number.

It is an amenable number.

28284021 is a deficient number, since it is larger than the sum of its proper divisors (14020163).

28284021 is a wasteful number, since it uses less digits than its factorization.

28284021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 741 (or 738 counting only the distinct ones).

The product of its (nonzero) digits is 2048, while the sum is 27.

The square root of 28284021 is about 5318.2723698585. The cubic root of 28284021 is about 304.6821772167.

The spelling of 28284021 in words is "twenty-eight million, two hundred eighty-four thousand, twenty-one".