28239999 has 4 divisors (see below), whose sum is σ = 37653336. Its totient is φ = 18826664.

The previous prime is 28239989. The next prime is 28240013. The reversal of 28239999 is 99993282.

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 28239999 - 2⁹ = 28239487 is a prime.

28239999 is a modest number, since divided by 9999 gives 2823 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28239989) 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, 4706664 + ... + 4706669.

It is an arithmetic number, because the mean of its divisors is an integer number (9413334).

Almost surely, 2^28239999 is an apocalyptic number.

28239999 is a deficient number, since it is larger than the sum of its proper divisors (9413337).

28239999 is an equidigital number, since it uses as much as digits as its factorization.

28239999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9413336.

The product of its digits is 629856, while the sum is 51.

The square root of 28239999 is about 5314.1320081458. The cubic root of 28239999 is about 304.5240233311.

The spelling of 28239999 in words is "twenty-eight million, two hundred thirty-nine thousand, nine hundred ninety-nine".