28686813 has 4 divisors (see below), whose sum is σ = 38249088. Its totient is φ = 19124540.

The previous prime is 28686809. The next prime is 28686817. The reversal of 28686813 is 31868682.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (28686809) and next prime (28686817).

It is a cyclic number.

It is not a de Polignac number, because 28686813 - 2² = 28686809 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28686817) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4781133 + ... + 4781138.

It is an arithmetic number, because the mean of its divisors is an integer number (9562272).

Almost surely, 2^28686813 is an apocalyptic number.

It is an amenable number.

28686813 is a deficient number, since it is larger than the sum of its proper divisors (9562275).

28686813 is an equidigital number, since it uses as much as digits as its factorization.

28686813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9562274.

The product of its digits is 110592, while the sum is 42.

The square root of 28686813 is about 5356.0071881953. The cubic root of 28686813 is about 306.1216889667.

The spelling of 28686813 in words is "twenty-eight million, six hundred eighty-six thousand, eight hundred thirteen".