28157 has 4 divisors (see below), whose sum is σ = 28956. Its totient is φ = 27360.

The previous prime is 28151. The next prime is 28163. The reversal of 28157 is 75182.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 75182 = 2 ⋅37591.

It is an interprime number because it is at equal distance from previous prime (28151) and next prime (28163).

It can be written as a sum of positive squares in 2 ways, for example, as 10201 + 17956 = 101^2 + 134^2 .

It is a cyclic number.

It is not a de Polignac number, because 28157 - 2⁸ = 27901 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28151) 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, 344 + ... + 417.

It is an arithmetic number, because the mean of its divisors is an integer number (7239).

2²⁸¹⁵⁷ is an apocalyptic number.

It is an amenable number.

28157 is a deficient number, since it is larger than the sum of its proper divisors (799).

28157 is an equidigital number, since it uses as much as digits as its factorization.

28157 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 798.

The product of its digits is 560, while the sum is 23.

The square root of 28157 is about 167.8004767574. The cubic root of 28157 is about 30.4225392635.

The spelling of 28157 in words is "twenty-eight thousand, one hundred fifty-seven".