28189905 has 32 divisors (see below), whose sum is σ = 46811520. Its totient is φ = 14476800.

The previous prime is 28189891. The next prime is 28189921. The reversal of 28189905 is 50998182.

It is a happy number.

It is not a de Polignac number, because 28189905 - 2⁵ = 28189873 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 46605 + ... + 47205.

It is an arithmetic number, because the mean of its divisors is an integer number (1462860).

Almost surely, 2^28189905 is an apocalyptic number.

It is an amenable number.

28189905 is a deficient number, since it is larger than the sum of its proper divisors (18621615).

28189905 is a wasteful number, since it uses less digits than its factorization.

28189905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 721.

The product of its (nonzero) digits is 51840, while the sum is 42.

The square root of 28189905 is about 5309.4166346219. The cubic root of 28189905 is about 304.3438550606.

The spelling of 28189905 in words is "twenty-eight million, one hundred eighty-nine thousand, nine hundred five".