28231388 has 12 divisors (see below), whose sum is σ = 50142792. Its totient is φ = 13904880.

The previous prime is 28231387. The next prime is 28231391. The reversal of 28231388 is 88313282.

It is a happy number.

It is a super-2 number, since 2×28231388² = 1594022536813088, which contains 22 as substring.

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 3 ways as a sum of consecutive naturals, for example, 52403 + ... + 52938.

It is an arithmetic number, because the mean of its divisors is an integer number (4178566).

Almost surely, 2^28231388 is an apocalyptic number.

It is an amenable number.

28231388 is a deficient number, since it is larger than the sum of its proper divisors (21911404).

28231388 is a wasteful number, since it uses less digits than its factorization.

28231388 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 105412 (or 105410 counting only the distinct ones).

The product of its digits is 18432, while the sum is 35.

The square root of 28231388 is about 5313.3217482099. The cubic root of 28231388 is about 304.4930681489.

The spelling of 28231388 in words is "twenty-eight million, two hundred thirty-one thousand, three hundred eighty-eight".