28591931 has 4 divisors (see below), whose sum is σ = 29076600. Its totient is φ = 28107264.

The previous prime is 28591919. The next prime is 28591939. The reversal of 28591931 is 13919582.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 28591931 - 2⁶ = 28591867 is a prime.

It is a super-2 number, since 2×28591931² = 1634997036617522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28591939) 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, 242246 + ... + 242363.

It is an arithmetic number, because the mean of its divisors is an integer number (7269150).

Almost surely, 2^28591931 is an apocalyptic number.

28591931 is a deficient number, since it is larger than the sum of its proper divisors (484669).

28591931 is an equidigital number, since it uses as much as digits as its factorization.

28591931 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 484668.

The product of its digits is 19440, while the sum is 38.

The square root of 28591931 is about 5347.1423209038. The cubic root of 28591931 is about 305.7838157218.

The spelling of 28591931 in words is "twenty-eight million, five hundred ninety-one thousand, nine hundred thirty-one".