28557217 has 4 divisors (see below), whose sum is σ = 30753940. Its totient is φ = 26360496.

The previous prime is 28557173. The next prime is 28557227. The reversal of 28557217 is 71275582.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1766241 + 26790976 = 1329^2 + 5176^2 .

It is a cyclic number.

It is not a de Polignac number, because 28557217 - 2²³ = 20168609 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28557227) 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, 1098342 + ... + 1098367.

It is an arithmetic number, because the mean of its divisors is an integer number (7688485).

Almost surely, 2^28557217 is an apocalyptic number.

It is an amenable number.

28557217 is a deficient number, since it is larger than the sum of its proper divisors (2196723).

28557217 is a wasteful number, since it uses less digits than its factorization.

28557217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2196722.

The product of its digits is 39200, while the sum is 37.

The square root of 28557217 is about 5343.8953021181. The cubic root of 28557217 is about 305.6600129815.

The spelling of 28557217 in words is "twenty-eight million, five hundred fifty-seven thousand, two hundred seventeen".