28278923 has 4 divisors (see below), whose sum is σ = 28543320. Its totient is φ = 28014528.

The previous prime is 28278911. The next prime is 28278931. The reversal of 28278923 is 32987282.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 32987282 = 2 ⋅16493641.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28278923 is a prime.

It is not an unprimeable number, because it can be changed into a prime (28278953) 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, 132038 + ... + 132251.

It is an arithmetic number, because the mean of its divisors is an integer number (7135830).

Almost surely, 2^28278923 is an apocalyptic number.

28278923 is a deficient number, since it is larger than the sum of its proper divisors (264397).

28278923 is a wasteful number, since it uses less digits than its factorization.

28278923 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 264396.

The product of its digits is 96768, while the sum is 41.

The square root of 28278923 is about 5317.7930572748. The cubic root of 28278923 is about 304.6638704954.

The spelling of 28278923 in words is "twenty-eight million, two hundred seventy-eight thousand, nine hundred twenty-three".