28389431 has 4 divisors (see below), whose sum is σ = 32445072. Its totient is φ = 24333792.

The previous prime is 28389409. The next prime is 28389467. The reversal of 28389431 is 13498382.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 13498382 = 2 ⋅6749191.

It is not a de Polignac number, because 28389431 - 2¹⁴ = 28373047 is a prime.

It is a super-2 number, since 2×28389431² = 1611919585007522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28389631) 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, 2027810 + ... + 2027823.

It is an arithmetic number, because the mean of its divisors is an integer number (8111268).

Almost surely, 2^28389431 is an apocalyptic number.

28389431 is a deficient number, since it is larger than the sum of its proper divisors (4055641).

28389431 is an equidigital number, since it uses as much as digits as its factorization.

28389431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4055640.

The product of its digits is 41472, while the sum is 38.

The square root of 28389431 is about 5328.1733267603. The cubic root of 28389431 is about 305.0602084846.

The spelling of 28389431 in words is "twenty-eight million, three hundred eighty-nine thousand, four hundred thirty-one".