28218239 has 4 divisors (see below), whose sum is σ = 32249424. Its totient is φ = 24187056.

The previous prime is 28218221. The next prime is 28218259. The reversal of 28218239 is 93281282.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 28218239 - 2²⁰ = 27169663 is a prime.

It is a super-2 number, since 2×28218239² = 1592538024522242, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 28218199 and 28218208.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28218259) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2015582 + ... + 2015595.

It is an arithmetic number, because the mean of its divisors is an integer number (8062356).

Almost surely, 2^28218239 is an apocalyptic number.

28218239 is a deficient number, since it is larger than the sum of its proper divisors (4031185).

28218239 is an equidigital number, since it uses as much as digits as its factorization.

28218239 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4031184.

The product of its digits is 13824, while the sum is 35.

The square root of 28218239 is about 5312.0842425549. The cubic root of 28218239 is about 304.4457874282.

The spelling of 28218239 in words is "twenty-eight million, two hundred eighteen thousand, two hundred thirty-nine".