28001905 has 8 divisors (see below), whose sum is σ = 33859584. Its totient is φ = 22230000.

The previous prime is 28001899. The next prime is 28001921. The reversal of 28001905 is 50910082.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 28001905 - 2¹¹ = 27999857 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 28001905.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 20721 + ... + 22030.

It is an arithmetic number, because the mean of its divisors is an integer number (4232448).

Almost surely, 2^28001905 is an apocalyptic number.

It is an amenable number.

28001905 is a deficient number, since it is larger than the sum of its proper divisors (5857679).

28001905 is a wasteful number, since it uses less digits than its factorization.

28001905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42887.

The product of its (nonzero) digits is 720, while the sum is 25.

The square root of 28001905 is about 5291.6826246479. The cubic root of 28001905 is about 303.6657835814.

Adding to 28001905 its reverse (50910082), we get a palindrome (78911987).

The spelling of 28001905 in words is "twenty-eight million, one thousand, nine hundred five".