28218569 has 4 divisors (see below), whose sum is σ = 28294596. Its totient is φ = 28142544.

The previous prime is 28218559. The next prime is 28218571. The reversal of 28218569 is 96581282.

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 15523600 + 12694969 = 3940^2 + 3563^2 .

It is a cyclic number.

It is not a de Polignac number, because 28218569 - 2²⁰ = 27169993 is a prime.

It is a super-2 number, since 2×28218569² = 1592575272815522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28218559) by changing a digit.

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, 37454 + ... + 38199.

It is an arithmetic number, because the mean of its divisors is an integer number (7073649).

Almost surely, 2^28218569 is an apocalyptic number.

It is an amenable number.

28218569 is a deficient number, since it is larger than the sum of its proper divisors (76027).

28218569 is an equidigital number, since it uses as much as digits as its factorization.

28218569 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 76026.

The product of its digits is 69120, while the sum is 41.

The square root of 28218569 is about 5312.1153037185. The cubic root of 28218569 is about 304.4469742105.

The spelling of 28218569 in words is "twenty-eight million, two hundred eighteen thousand, five hundred sixty-nine".