28123439 has 4 divisors (see below), whose sum is σ = 29603640. Its totient is φ = 26643240.

The previous prime is 28123427. The next prime is 28123483. The reversal of 28123439 is 93432182.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 93432182 = 2 ⋅46716091.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28123439 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 (28123409) 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, 740072 + ... + 740109.

It is an arithmetic number, because the mean of its divisors is an integer number (7400910).

Almost surely, 2^28123439 is an apocalyptic number.

28123439 is a deficient number, since it is larger than the sum of its proper divisors (1480201).

28123439 is a wasteful number, since it uses less digits than its factorization.

28123439 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1480200.

The product of its digits is 10368, while the sum is 32.

The square root of 28123439 is about 5303.1536843656. The cubic root of 28123439 is about 304.1044734125.

The spelling of 28123439 in words is "twenty-eight million, one hundred twenty-three thousand, four hundred thirty-nine".