28805921 has 4 divisors (see below), whose sum is σ = 28846272. Its totient is φ = 28765572.

The previous prime is 28805893. The next prime is 28805929. The reversal of 28805921 is 12950882.

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 a cyclic number.

It is not a de Polignac number, because 28805921 - 2⁶ = 28805857 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (28805929) 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, 19085 + ... + 20538.

It is an arithmetic number, because the mean of its divisors is an integer number (7211568).

Almost surely, 2^28805921 is an apocalyptic number.

It is an amenable number.

28805921 is a deficient number, since it is larger than the sum of its proper divisors (40351).

28805921 is an equidigital number, since it uses as much as digits as its factorization.

28805921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40350.

The product of its (nonzero) digits is 11520, while the sum is 35.

The square root of 28805921 is about 5367.1147742525. The cubic root of 28805921 is about 306.5447776206.

The spelling of 28805921 in words is "twenty-eight million, eight hundred five thousand, nine hundred twenty-one".