28155609 has 6 divisors (see below), whose sum is σ = 40669226. Its totient is φ = 18770400.

The previous prime is 28155601. The next prime is 28155613. The reversal of 28155609 is 90655182.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 24651225 + 3504384 = 4965^2 + 1872^2 .

It is not a de Polignac number, because 28155609 - 2³ = 28155601 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28155601) 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, 1564192 + ... + 1564209.

Almost surely, 2^28155609 is an apocalyptic number.

It is an amenable number.

28155609 is a deficient number, since it is larger than the sum of its proper divisors (12513617).

28155609 is a wasteful number, since it uses less digits than its factorization.

28155609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3128407 (or 3128404 counting only the distinct ones).

The product of its (nonzero) digits is 21600, while the sum is 36.

The square root of 28155609 is about 5306.1859183410. The cubic root of 28155609 is about 304.2203828152.

The spelling of 28155609 in words is "twenty-eight million, one hundred fifty-five thousand, six hundred nine".