28920121 has 4 divisors (see below), whose sum is σ = 28933200. Its totient is φ = 28907044.

The previous prime is 28920113. The next prime is 28920149. The reversal of 28920121 is 12102982.

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 28920121 - 2³ = 28920113 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28620121) 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, 2311 + ... + 7948.

It is an arithmetic number, because the mean of its divisors is an integer number (7233300).

Almost surely, 2^28920121 is an apocalyptic number.

It is an amenable number.

28920121 is a deficient number, since it is larger than the sum of its proper divisors (13079).

28920121 is a wasteful number, since it uses less digits than its factorization.

28920121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13078.

The product of its (nonzero) digits is 576, while the sum is 25.

The square root of 28920121 is about 5377.7431139838. The cubic root of 28920121 is about 306.9493385829.

The spelling of 28920121 in words is "twenty-eight million, nine hundred twenty thousand, one hundred twenty-one".