28158309 has 6 divisors (see below), whose sum is σ = 40673126. Its totient is φ = 18772200.

The previous prime is 28158289. The next prime is 28158337. The reversal of 28158309 is 90385182.

It can be written as a sum of positive squares in only one way, i.e., 14630625 + 13527684 = 3825^2 + 3678^2 .

It is not a de Polignac number, because 28158309 - 2⁷ = 28158181 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28157309) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1564342 + ... + 1564359.

Almost surely, 2^28158309 is an apocalyptic number.

It is an amenable number.

28158309 is a deficient number, since it is larger than the sum of its proper divisors (12514817).

28158309 is a wasteful number, since it uses less digits than its factorization.

28158309 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3128707 (or 3128704 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 36.

The square root of 28158309 is about 5306.4403322755. The cubic root of 28158309 is about 304.2301069733.

The spelling of 28158309 in words is "twenty-eight million, one hundred fifty-eight thousand, three hundred nine".