28431891 has 10 divisors (see below), whose sum is σ = 42472452. Its totient is φ = 18954540.

The previous prime is 28431889. The next prime is 28431911. The reversal of 28431891 is 19813482.

It is not a de Polignac number, because 28431891 - 2¹ = 28431889 is a prime.

It is not an unprimeable number, because it can be changed into a prime (28431881) 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 9 ways as a sum of consecutive naturals, for example, 175425 + ... + 175586.

Almost surely, 2^28431891 is an apocalyptic number.

28431891 is a deficient number, since it is larger than the sum of its proper divisors (14040561).

28431891 is an equidigital number, since it uses as much as digits as its factorization.

28431891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 351023 (or 351014 counting only the distinct ones).

The product of its digits is 13824, while the sum is 36.

The square root of 28431891 is about 5332.1563180387. The cubic root of 28431891 is about 305.2122181564.

The spelling of 28431891 in words is "twenty-eight million, four hundred thirty-one thousand, eight hundred ninety-one".