28408509 has 16 divisors (see below), whose sum is σ = 43067200. Its totient is φ = 18497808.

The previous prime is 28408507. The next prime is 28408517. The reversal of 28408509 is 90580482.

It is not a de Polignac number, because 28408509 - 2¹ = 28408507 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 (28408507) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11074 + ... + 13395.

It is an arithmetic number, because the mean of its divisors is an integer number (2691700).

Almost surely, 2^28408509 is an apocalyptic number.

It is an amenable number.

28408509 is a deficient number, since it is larger than the sum of its proper divisors (14658691).

28408509 is a wasteful number, since it uses less digits than its factorization.

28408509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24521 (or 24515 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 36.

The square root of 28408509 is about 5329.9633206993. The cubic root of 28408509 is about 305.1285277529.

The spelling of 28408509 in words is "twenty-eight million, four hundred eight thousand, five hundred nine".