28309005 has 24 divisors (see below), whose sum is σ = 49375872. Its totient is φ = 15003744.

The previous prime is 28309003. The next prime is 28309009. The reversal of 28309005 is 50090382.

It is not a de Polignac number, because 28309005 - 2¹ = 28309003 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 28309005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28309003) 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, 5632 + ... + 9398.

It is an arithmetic number, because the mean of its divisors is an integer number (2057328).

Almost surely, 2^28309005 is an apocalyptic number.

It is an amenable number.

28309005 is a deficient number, since it is larger than the sum of its proper divisors (21066867).

28309005 is a wasteful number, since it uses less digits than its factorization.

28309005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3945 (or 3942 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 27.

The square root of 28309005 is about 5320.6207344632. The cubic root of 28309005 is about 304.7718620045.

Adding to 28309005 its reverse (50090382), we get a palindrome (78399387).

The spelling of 28309005 in words is "twenty-eight million, three hundred nine thousand, five".