28438509 has 24 divisors (see below), whose sum is σ = 42028000. Its totient is φ = 17091360.

The previous prime is 28438507. The next prime is 28438513. The reversal of 28438509 is 90583482.

It is a happy number.

It is not a de Polignac number, because 28438509 - 2¹ = 28438507 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 (28438507) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 56742 + ... + 57240.

Almost surely, 2^28438509 is an apocalyptic number.

It is an amenable number.

28438509 is a deficient number, since it is larger than the sum of its proper divisors (13589491).

28438509 is a wasteful number, since it uses less digits than its factorization.

28438509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 681 (or 670 counting only the distinct ones).

The product of its (nonzero) digits is 69120, while the sum is 39.

The square root of 28438509 is about 5332.7768563854. The cubic root of 28438509 is about 305.2358974087.

The spelling of 28438509 in words is "twenty-eight million, four hundred thirty-eight thousand, five hundred nine".