28172305 has 16 divisors (see below), whose sum is σ = 39427200. Its totient is φ = 19316976.

The previous prime is 28172299. The next prime is 28172341. The reversal of 28172305 is 50327182.

It is not a de Polignac number, because 28172305 - 2¹¹ = 28170257 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6499 + ... + 9928.

It is an arithmetic number, because the mean of its divisors is an integer number (2464200).

Almost surely, 2^28172305 is an apocalyptic number.

It is an amenable number.

28172305 is a deficient number, since it is larger than the sum of its proper divisors (11254895).

28172305 is an equidigital number, since it uses as much as digits as its factorization.

28172305 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16453 (or 16439 counting only the distinct ones).

The product of its (nonzero) digits is 3360, while the sum is 28.

The square root of 28172305 is about 5307.7589432829. The cubic root of 28172305 is about 304.2805041674.

Adding to 28172305 its reverse (50327182), we get a palindrome (78499487).

The spelling of 28172305 in words is "twenty-eight million, one hundred seventy-two thousand, three hundred five".