28372921 has 4 divisors (see below), whose sum is σ = 28547152. Its totient is φ = 28198692.

The previous prime is 28372901. The next prime is 28372931. The reversal of 28372921 is 12927382.

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 28372921 - 2⁷ = 28372793 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28372901) 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, 86871 + ... + 87196.

It is an arithmetic number, because the mean of its divisors is an integer number (7136788).

Almost surely, 2^28372921 is an apocalyptic number.

It is an amenable number.

28372921 is a deficient number, since it is larger than the sum of its proper divisors (174231).

28372921 is a wasteful number, since it uses less digits than its factorization.

28372921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 174230.

The product of its digits is 12096, while the sum is 34.

The square root of 28372921 is about 5326.6237899818. The cubic root of 28372921 is about 305.0010606431.

The spelling of 28372921 in words is "twenty-eight million, three hundred seventy-two thousand, nine hundred twenty-one".