28431111 has 4 divisors (see below), whose sum is σ = 37908152. Its totient is φ = 18954072.

The previous prime is 28431083. The next prime is 28431113. The reversal of 28431111 is 11113482.

It is a happy number.

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

It is not a de Polignac number, because 28431111 - 2⁵ = 28431079 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28431113) 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 3 ways as a sum of consecutive naturals, for example, 4738516 + ... + 4738521.

It is an arithmetic number, because the mean of its divisors is an integer number (9477038).

Almost surely, 2^28431111 is an apocalyptic number.

28431111 is a deficient number, since it is larger than the sum of its proper divisors (9477041).

28431111 is an equidigital number, since it uses as much as digits as its factorization.

28431111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9477040.

The product of its digits is 192, while the sum is 21.

The square root of 28431111 is about 5332.0831763955. The cubic root of 28431111 is about 305.2094270687.

Adding to 28431111 its reverse (11113482), we get a palindrome (39544593).

The spelling of 28431111 in words is "twenty-eight million, four hundred thirty-one thousand, one hundred eleven".