28681109 has 4 divisors (see below), whose sum is σ = 29222316. Its totient is φ = 28139904.

The previous prime is 28681097. The next prime is 28681117. The reversal of 28681109 is 90118682.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 90118682 = 2 ⋅45059341.

It can be written as a sum of positive squares in 2 ways, for example, as 24780484 + 3900625 = 4978^2 + 1975^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28681109 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28681199) 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, 270524 + ... + 270629.

It is an arithmetic number, because the mean of its divisors is an integer number (7305579).

Almost surely, 2^28681109 is an apocalyptic number.

It is an amenable number.

28681109 is a deficient number, since it is larger than the sum of its proper divisors (541207).

28681109 is an equidigital number, since it uses as much as digits as its factorization.

28681109 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 541206.

The product of its (nonzero) digits is 6912, while the sum is 35.

The square root of 28681109 is about 5355.4746755073. The cubic root of 28681109 is about 306.1013981818.

The spelling of 28681109 in words is "twenty-eight million, six hundred eighty-one thousand, one hundred nine".