28021937 has 4 divisors (see below), whose sum is σ = 28049700. Its totient is φ = 27994176.

The previous prime is 28021919. The next prime is 28021943. The reversal of 28021937 is 73912082.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 73912082 = 2 ⋅36956041.

It can be written as a sum of positive squares in 2 ways, for example, as 26584336 + 1437601 = 5156^2 + 1199^2 .

It is a cyclic number.

It is not a de Polignac number, because 28021937 - 2¹⁴ = 28005553 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28021907) 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 3 ways as a sum of consecutive naturals, for example, 12308 + ... + 14405.

It is an arithmetic number, because the mean of its divisors is an integer number (7012425).

Almost surely, 2^28021937 is an apocalyptic number.

It is an amenable number.

28021937 is a deficient number, since it is larger than the sum of its proper divisors (27763).

28021937 is a wasteful number, since it uses less digits than its factorization.

28021937 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27762.

The product of its (nonzero) digits is 6048, while the sum is 32.

The square root of 28021937 is about 5293.5750679479. The cubic root of 28021937 is about 303.7381784535.

The spelling of 28021937 in words is "twenty-eight million, twenty-one thousand, nine hundred thirty-seven".