12816809 has 4 divisors (see below), whose sum is σ = 12824916. Its totient is φ = 12808704.

The previous prime is 12816751. The next prime is 12816821. The reversal of 12816809 is 90861821.

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: 90861821 = 17 ⋅5344813.

It can be written as a sum of positive squares in 2 ways, for example, as 426409 + 12390400 = 653^2 + 3520^2 .

It is a cyclic number.

It is not a de Polignac number, because 12816809 - 2⁸ = 12816553 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (12816889) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 824 + ... + 5129.

It is an arithmetic number, because the mean of its divisors is an integer number (3206229).

Almost surely, 2^12816809 is an apocalyptic number.

It is an amenable number.

12816809 is a deficient number, since it is larger than the sum of its proper divisors (8107).

12816809 is an equidigital number, since it uses as much as digits as its factorization.

12816809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8106.

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

The square root of 12816809 is about 3580.0571224493. The cubic root of 12816809 is about 234.0237697139.

The spelling of 12816809 in words is "twelve million, eight hundred sixteen thousand, eight hundred nine".