28557181 has 4 divisors (see below), whose sum is σ = 28648732. Its totient is φ = 28465632.

The previous prime is 28557173. The next prime is 28557227. The reversal of 28557181 is 18175582.

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 562500 + 27994681 = 750^2 + 5291^2 .

It is a cyclic number.

It is not a de Polignac number, because 28557181 - 2³ = 28557173 is a prime.

It is a super-2 number, since 2×28557181² = 1631025173333522, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 28557181.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28551181) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 45306 + ... + 45931.

It is an arithmetic number, because the mean of its divisors is an integer number (7162183).

Almost surely, 2^28557181 is an apocalyptic number.

It is an amenable number.

28557181 is a deficient number, since it is larger than the sum of its proper divisors (91551).

28557181 is an equidigital number, since it uses as much as digits as its factorization.

28557181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 91550.

The product of its digits is 22400, while the sum is 37.

The square root of 28557181 is about 5343.8919337876. The cubic root of 28557181 is about 305.6598845403.

The spelling of 28557181 in words is "twenty-eight million, five hundred fifty-seven thousand, one hundred eighty-one".