28156105 has 4 divisors (see below), whose sum is σ = 33787332. Its totient is φ = 22524880.

The previous prime is 28156067. The next prime is 28156123. The reversal of 28156105 is 50165182.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 50165182 = 2 ⋅25082591.

It can be written as a sum of positive squares in 2 ways, for example, as 7689529 + 20466576 = 2773^2 + 4524^2 .

It is not a de Polignac number, because 28156105 - 2⁹ = 28155593 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, 2815606 + ... + 2815615.

It is an arithmetic number, because the mean of its divisors is an integer number (8446833).

Almost surely, 2^28156105 is an apocalyptic number.

It is an amenable number.

28156105 is a deficient number, since it is larger than the sum of its proper divisors (5631227).

28156105 is an equidigital number, since it uses as much as digits as its factorization.

28156105 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5631226.

The product of its (nonzero) digits is 2400, while the sum is 28.

The square root of 28156105 is about 5306.2326560376. The cubic root of 28156105 is about 304.2221692257. Note that the first 3 decimals are identical.

The spelling of 28156105 in words is "twenty-eight million, one hundred fifty-six thousand, one hundred five".