28138105 has 4 divisors (see below), whose sum is σ = 33765732. Its totient is φ = 22510480.

The previous prime is 28138073. The next prime is 28138127. The reversal of 28138105 is 50183182.

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 14830201 + 13307904 = 3851^2 + 3648^2 .

It is not a de Polignac number, because 28138105 - 2⁵ = 28138073 is a prime.

It is a Duffinian 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, 2813806 + ... + 2813815.

It is an arithmetic number, because the mean of its divisors is an integer number (8441433).

Almost surely, 2^28138105 is an apocalyptic number.

It is an amenable number.

28138105 is a deficient number, since it is larger than the sum of its proper divisors (5627627).

28138105 is an equidigital number, since it uses as much as digits as its factorization.

28138105 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5627626.

The product of its (nonzero) digits is 1920, while the sum is 28.

The square root of 28138105 is about 5304.5362662536. The cubic root of 28138105 is about 304.1573263744.

The spelling of 28138105 in words is "twenty-eight million, one hundred thirty-eight thousand, one hundred five".