12805821 has 48 divisors (see below), whose sum is σ = 22364160. Its totient is φ = 6907680.

The previous prime is 12805813. The next prime is 12805823. The reversal of 12805821 is 12850821.

12805821 is a `hidden beast` number, since 1 + 2 + 80 + 582 + 1 = 666.

It is not a de Polignac number, because 12805821 - 2³ = 12805813 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12805823) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 154246 + ... + 154328.

It is an arithmetic number, because the mean of its divisors is an integer number (465920).

Almost surely, 2^12805821 is an apocalyptic number.

It is an amenable number.

12805821 is a deficient number, since it is larger than the sum of its proper divisors (9558339).

12805821 is a wasteful number, since it uses less digits than its factorization.

12805821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 206 (or 203 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 27.

The square root of 12805821 is about 3578.5221810127. The cubic root of 12805821 is about 233.9568734899.

The spelling of 12805821 in words is "twelve million, eight hundred five thousand, eight hundred twenty-one".