28508921 has 8 divisors (see below), whose sum is σ = 32620224. Its totient is φ = 24407280.

The previous prime is 28508903. The next prime is 28508947. The reversal of 28508921 is 12980582.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 28508921 - 2¹⁴ = 28492537 is a prime.

It is not an unprimeable number, because it can be changed into a prime (28508321) 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 7 ways as a sum of consecutive naturals, for example, 5771 + ... + 9503.

It is an arithmetic number, because the mean of its divisors is an integer number (4077528).

Almost surely, 2^28508921 is an apocalyptic number.

It is an amenable number.

28508921 is a deficient number, since it is larger than the sum of its proper divisors (4111303).

28508921 is a wasteful number, since it uses less digits than its factorization.

28508921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4831.

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

The square root of 28508921 is about 5339.3745888447. The cubic root of 28508921 is about 305.4876048912.

The spelling of 28508921 in words is "twenty-eight million, five hundred eight thousand, nine hundred twenty-one".