28143989 has 4 divisors (see below), whose sum is σ = 28217856. Its totient is φ = 28070124.

The previous prime is 28143971. The next prime is 28144033. The reversal of 28143989 is 98934182.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 98934182 = 2 ⋅49467091.

It is a cyclic number.

It is not a de Polignac number, because 28143989 - 2⁸ = 28143733 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 (28145989) 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, 36359 + ... + 37124.

It is an arithmetic number, because the mean of its divisors is an integer number (7054464).

Almost surely, 2^28143989 is an apocalyptic number.

It is an amenable number.

28143989 is a deficient number, since it is larger than the sum of its proper divisors (73867).

28143989 is an equidigital number, since it uses as much as digits as its factorization.

28143989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73866.

The product of its digits is 124416, while the sum is 44.

The square root of 28143989 is about 5305.0908569034. The cubic root of 28143989 is about 304.1785258236.

The spelling of 28143989 in words is "twenty-eight million, one hundred forty-three thousand, nine hundred eighty-nine".