28031231 has 4 divisors (see below), whose sum is σ = 28085352. Its totient is φ = 27977112.

The previous prime is 28031191. The next prime is 28031239. The reversal of 28031231 is 13213082.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 13213082 = 2 ⋅6606541.

It is a cyclic number.

It is not a de Polignac number, because 28031231 - 2¹⁰ = 28030207 is a prime.

It is a super-2 number, since 2×28031231² = 1571499822750722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28031239) 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, 26276 + ... + 27321.

It is an arithmetic number, because the mean of its divisors is an integer number (7021338).

Almost surely, 2^28031231 is an apocalyptic number.

28031231 is a deficient number, since it is larger than the sum of its proper divisors (54121).

28031231 is an equidigital number, since it uses as much as digits as its factorization.

28031231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54120.

The product of its (nonzero) digits is 288, while the sum is 20.

The square root of 28031231 is about 5294.4528518063. The cubic root of 28031231 is about 303.7717548927.

The spelling of 28031231 in words is "twenty-eight million, thirty-one thousand, two hundred thirty-one".