28530405 has 24 divisors (see below), whose sum is σ = 49608312. Its totient is φ = 15168384.

The previous prime is 28530391. The next prime is 28530407. The reversal of 28530405 is 50403582.

It can be written as a sum of positive squares in 4 ways, for example, as 1718721 + 26811684 = 1311^2 + 5178^2 .

It is not a de Polignac number, because 28530405 - 2⁷ = 28530277 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28530407) 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, 17067 + ... + 18663.

It is an arithmetic number, because the mean of its divisors is an integer number (2067013).

Almost surely, 2^28530405 is an apocalyptic number.

It is an amenable number.

28530405 is a deficient number, since it is larger than the sum of its proper divisors (21077907).

28530405 is a wasteful number, since it uses less digits than its factorization.

28530405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2005 (or 2002 counting only the distinct ones).

The product of its (nonzero) digits is 4800, while the sum is 27.

The square root of 28530405 is about 5341.3860560720. The cubic root of 28530405 is about 305.5643229563.

Adding to 28530405 its reverse (50403582), we get a palindrome (78933987).

The spelling of 28530405 in words is "twenty-eight million, five hundred thirty thousand, four hundred five".