28223665 has 4 divisors (see below), whose sum is σ = 33868404. Its totient is φ = 22578928.

The previous prime is 28223659. The next prime is 28223687. The reversal of 28223665 is 56632282.

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 15713296 + 12510369 = 3964^2 + 3537^2 .

It is a cyclic number.

It is not a de Polignac number, because 28223665 - 2⁵ = 28223633 is a prime.

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 28223665.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2822362 + ... + 2822371.

It is an arithmetic number, because the mean of its divisors is an integer number (8467101).

Almost surely, 2^28223665 is an apocalyptic number.

It is an amenable number.

28223665 is a deficient number, since it is larger than the sum of its proper divisors (5644739).

28223665 is an equidigital number, since it uses as much as digits as its factorization.

28223665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5644738.

The product of its digits is 34560, while the sum is 34.

The square root of 28223665 is about 5312.5949403281. The cubic root of 28223665 is about 304.4652998315.

The spelling of 28223665 in words is "twenty-eight million, two hundred twenty-three thousand, six hundred sixty-five".