28156257 has 24 divisors (see below), whose sum is σ = 41670720. Its totient is φ = 18315360.

The previous prime is 28156241. The next prime is 28156259. The reversal of 28156257 is 75265182.

It is a happy number.

28156257 is a `hidden beast` number, since 28 + 1 + 5 + 625 + 7 = 666.

It is not a de Polignac number, because 28156257 - 2⁴ = 28156241 is a prime.

It is not an unprimeable number, because it can be changed into a prime (28156259) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 88663 + ... + 88979.

It is an arithmetic number, because the mean of its divisors is an integer number (1736280).

Almost surely, 2^28156257 is an apocalyptic number.

It is an amenable number.

28156257 is a deficient number, since it is larger than the sum of its proper divisors (13514463).

28156257 is a wasteful number, since it uses less digits than its factorization.

28156257 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 533 (or 530 counting only the distinct ones).

The product of its digits is 33600, while the sum is 36.

The square root of 28156257 is about 5306.2469787977. The cubic root of 28156257 is about 304.2227166698. Note that the first 3 decimals are identical.

The spelling of 28156257 in words is "twenty-eight million, one hundred fifty-six thousand, two hundred fifty-seven".