28158805 has 4 divisors (see below), whose sum is σ = 33790572. Its totient is φ = 22527040.

The previous prime is 28158787. The next prime is 28158811. The reversal of 28158805 is 50885182.

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 21141604 + 7017201 = 4598^2 + 2649^2 .

It is not a de Polignac number, because 28158805 - 2¹³ = 28150613 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, 2815876 + ... + 2815885.

It is an arithmetic number, because the mean of its divisors is an integer number (8447643).

Almost surely, 2^28158805 is an apocalyptic number.

It is an amenable number.

28158805 is a deficient number, since it is larger than the sum of its proper divisors (5631767).

28158805 is an equidigital number, since it uses as much as digits as its factorization.

28158805 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5631766.

The product of its (nonzero) digits is 25600, while the sum is 37.

The square root of 28158805 is about 5306.4870677313. The cubic root of 28158805 is about 304.2318932696.

The spelling of 28158805 in words is "twenty-eight million, one hundred fifty-eight thousand, eight hundred five".