28138789 has 6 divisors (see below), whose sum is σ = 32732934. Its totient is φ = 24118920.

The previous prime is 28138777. The next prime is 28138801. The reversal of 28138789 is 98783182.

It is an interprime number because it is at equal distance from previous prime (28138777) and next prime (28138801).

It can be written as a sum of positive squares in only one way, i.e., 17994564 + 10144225 = 4242^2 + 3185^2 .

It is not a de Polignac number, because 28138789 - 2¹⁹ = 27614501 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 (28138709) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 287082 + ... + 287179.

It is an arithmetic number, because the mean of its divisors is an integer number (5455489).

Almost surely, 2^28138789 is an apocalyptic number.

It is an amenable number.

28138789 is a deficient number, since it is larger than the sum of its proper divisors (4594145).

28138789 is an equidigital number, since it uses as much as digits as its factorization.

28138789 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 574275 (or 574268 counting only the distinct ones).

The product of its digits is 193536, while the sum is 46.

The square root of 28138789 is about 5304.6007389812. The cubic root of 28138789 is about 304.1597909081.

The spelling of 28138789 in words is "twenty-eight million, one hundred thirty-eight thousand, seven hundred eighty-nine".