28205911 has 4 divisors (see below), whose sum is σ = 28738152. Its totient is φ = 27673672.

The previous prime is 28205897. The next prime is 28205921. The reversal of 28205911 is 11950282.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 28205911 - 2⁷ = 28205783 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 28205911.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28205921) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 266041 + ... + 266146.

It is an arithmetic number, because the mean of its divisors is an integer number (7184538).

Almost surely, 2^28205911 is an apocalyptic number.

28205911 is a deficient number, since it is larger than the sum of its proper divisors (532241).

28205911 is an equidigital number, since it uses as much as digits as its factorization.

28205911 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 532240.

The product of its (nonzero) digits is 1440, while the sum is 28.

The square root of 28205911 is about 5310.9237426271. The cubic root of 28205911 is about 304.4014454884.

The spelling of 28205911 in words is "twenty-eight million, two hundred five thousand, nine hundred eleven".