28115911 has 4 divisors (see below), whose sum is σ = 28138824. Its totient is φ = 28093000.

The previous prime is 28115897. The next prime is 28115939. The reversal of 28115911 is 11951182.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28115911 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 28115911.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28115951) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 9505 + ... + 12106.

It is an arithmetic number, because the mean of its divisors is an integer number (7034706).

Almost surely, 2^28115911 is an apocalyptic number.

28115911 is a deficient number, since it is larger than the sum of its proper divisors (22913).

28115911 is a wasteful number, since it uses less digits than its factorization.

28115911 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22912.

The product of its digits is 720, while the sum is 28.

The square root of 28115911 is about 5302.4438705186. The cubic root of 28115911 is about 304.0773370587.

The spelling of 28115911 in words is "twenty-eight million, one hundred fifteen thousand, nine hundred eleven".