28509111 has 8 divisors (see below), whose sum is σ = 42235760. Its totient is φ = 19006056.

The previous prime is 28509097. The next prime is 28509133. The reversal of 28509111 is 11190582.

It is not a de Polignac number, because 28509111 - 2⁵ = 28509079 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27), and also a Moran number because the ratio is a prime number: 1055893 = 28509111 / (2 + 8 + 5 + 0 + 9 + 1 + 1 + 1).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28509011) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 527920 + ... + 527973.

It is an arithmetic number, because the mean of its divisors is an integer number (5279470).

Almost surely, 2^28509111 is an apocalyptic number.

28509111 is a deficient number, since it is larger than the sum of its proper divisors (13726649).

28509111 is a wasteful number, since it uses less digits than its factorization.

28509111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1055902 (or 1055896 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 27.

The square root of 28509111 is about 5339.3923811610. The cubic root of 28509111 is about 305.4882835386.

Adding to 28509111 its reverse (11190582), we get a palindrome (39699693).

The spelling of 28509111 in words is "twenty-eight million, five hundred nine thousand, one hundred eleven".