28231257 has 4 divisors (see below), whose sum is σ = 37641680. Its totient is φ = 18820836.

The previous prime is 28231253. The next prime is 28231261. The reversal of 28231257 is 75213282.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (28231253) and next prime (28231261).

It is not a de Polignac number, because 28231257 - 2² = 28231253 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28231253) 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, 4705207 + ... + 4705212.

It is an arithmetic number, because the mean of its divisors is an integer number (9410420).

Almost surely, 2^28231257 is an apocalyptic number.

It is an amenable number.

28231257 is a deficient number, since it is larger than the sum of its proper divisors (9410423).

28231257 is an equidigital number, since it uses as much as digits as its factorization.

28231257 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9410422.

The product of its digits is 6720, while the sum is 30.

The square root of 28231257 is about 5313.3094206906. The cubic root of 28231257 is about 304.4925971761.

The spelling of 28231257 in words is "twenty-eight million, two hundred thirty-one thousand, two hundred fifty-seven".