28188205 has 4 divisors (see below), whose sum is σ = 33825852. Its totient is φ = 22550560.

The previous prime is 28188157. The next prime is 28188221. The reversal of 28188205 is 50288182.

It is a happy number.

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 15896169 + 12292036 = 3987^2 + 3506^2 .

It is not a de Polignac number, because 28188205 - 2⁹ = 28187693 is a prime.

It is a super-2 number, since 2×28188205² = 1589149802244050, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2818816 + ... + 2818825.

It is an arithmetic number, because the mean of its divisors is an integer number (8456463).

Almost surely, 2^28188205 is an apocalyptic number.

It is an amenable number.

28188205 is a deficient number, since it is larger than the sum of its proper divisors (5637647).

28188205 is an equidigital number, since it uses as much as digits as its factorization.

28188205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5637646.

The product of its (nonzero) digits is 10240, while the sum is 34.

The square root of 28188205 is about 5309.2565392906. The cubic root of 28188205 is about 304.3377370909.

The spelling of 28188205 in words is "twenty-eight million, one hundred eighty-eight thousand, two hundred five".