28890005 has 4 divisors (see below), whose sum is σ = 34668012. Its totient is φ = 23112000.

The previous prime is 28889989. The next prime is 28890031. The reversal of 28890005 is 50009882.

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 4218916 + 24671089 = 2054^2 + 4967^2 .

It is not a de Polignac number, because 28890005 - 2⁴ = 28889989 is a prime.

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, 2888996 + ... + 2889005.

It is an arithmetic number, because the mean of its divisors is an integer number (8667003).

Almost surely, 2^28890005 is an apocalyptic number.

It is an amenable number.

28890005 is a deficient number, since it is larger than the sum of its proper divisors (5778007).

28890005 is an equidigital number, since it uses as much as digits as its factorization.

28890005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5778006.

The product of its (nonzero) digits is 5760, while the sum is 32.

The square root of 28890005 is about 5374.9423252720. The cubic root of 28890005 is about 306.8427542327.

Adding to 28890005 its reverse (50009882), we get a palindrome (78899887).

The spelling of 28890005 in words is "twenty-eight million, eight hundred ninety thousand, five".