28231389 has 8 divisors (see below), whose sum is σ = 41824320. Its totient is φ = 18820908.

The previous prime is 28231387. The next prime is 28231391. The reversal of 28231389 is 98313282.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (28231387) and next prime (28231391).

It is not a de Polignac number, because 28231389 - 2¹ = 28231387 is a prime.

It is a super-2 number, since 2×28231389² = 1594022649738642, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28231387) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 522777 + ... + 522830.

It is an arithmetic number, because the mean of its divisors is an integer number (5228040).

Almost surely, 2^28231389 is an apocalyptic number.

It is an amenable number.

28231389 is a deficient number, since it is larger than the sum of its proper divisors (13592931).

28231389 is a wasteful number, since it uses less digits than its factorization.

28231389 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1045616 (or 1045610 counting only the distinct ones).

The product of its digits is 20736, while the sum is 36.

The square root of 28231389 is about 5313.3218423130. The cubic root of 28231389 is about 304.4930717441.

The spelling of 28231389 in words is "twenty-eight million, two hundred thirty-one thousand, three hundred eighty-nine".