28108813 has 4 divisors (see below), whose sum is σ = 28119420. Its totient is φ = 28098208.

The previous prime is 28108807. The next prime is 28108819. The reversal of 28108813 is 31880182.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 31880182 = 2 ⋅15940091.

It is an interprime number because it is at equal distance from previous prime (28108807) and next prime (28108819).

It can be written as a sum of positive squares in 2 ways, for example, as 11437924 + 16670889 = 3382^2 + 4083^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28108813 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 (28108819) 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, 2481 + ... + 7897.

It is an arithmetic number, because the mean of its divisors is an integer number (7029855).

Almost surely, 2^28108813 is an apocalyptic number.

It is an amenable number.

28108813 is a deficient number, since it is larger than the sum of its proper divisors (10607).

28108813 is an equidigital number, since it uses as much as digits as its factorization.

28108813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10606.

The product of its (nonzero) digits is 3072, while the sum is 31.

The square root of 28108813 is about 5301.7745142546. The cubic root of 28108813 is about 304.0517462987.

Adding to 28108813 its reverse (31880182), we get a palindrome (59988995).

The spelling of 28108813 in words is "twenty-eight million, one hundred eight thousand, eight hundred thirteen".