28323021 has 4 divisors (see below), whose sum is σ = 37764032. Its totient is φ = 18882012.

The previous prime is 28323011. The next prime is 28323047. The reversal of 28323021 is 12032382.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 28323021 - 2¹³ = 28314829 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 (28323011) 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, 4720501 + ... + 4720506.

It is an arithmetic number, because the mean of its divisors is an integer number (9441008).

Almost surely, 2^28323021 is an apocalyptic number.

It is an amenable number.

28323021 is a deficient number, since it is larger than the sum of its proper divisors (9441011).

28323021 is an equidigital number, since it uses as much as digits as its factorization.

28323021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9441010.

The product of its (nonzero) digits is 576, while the sum is 21.

The square root of 28323021 is about 5321.9377110222. The cubic root of 28323021 is about 304.8221519815.

The spelling of 28323021 in words is "twenty-eight million, three hundred twenty-three thousand, twenty-one".