28120111 has 16 divisors (see below), whose sum is σ = 30369600. Its totient is φ = 25982208.

The previous prime is 28120109. The next prime is 28120153. The reversal of 28120111 is 11102182.

It is a cyclic number.

It is not a de Polignac number, because 28120111 - 2¹ = 28120109 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28120511) 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 15 ways as a sum of consecutive naturals, for example, 78150 + ... + 78508.

It is an arithmetic number, because the mean of its divisors is an integer number (1898100).

Almost surely, 2^28120111 is an apocalyptic number.

28120111 is a deficient number, since it is larger than the sum of its proper divisors (2249489).

28120111 is a wasteful number, since it uses less digits than its factorization.

28120111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 498.

The product of its (nonzero) digits is 32, while the sum is 16.

The square root of 28120111 is about 5302.8398995255. The cubic root of 28120111 is about 304.0924774920.

Adding to 28120111 its reverse (11102182), we get a palindrome (39222293).

The spelling of 28120111 in words is "twenty-eight million, one hundred twenty thousand, one hundred eleven".