12555821 has 4 divisors (see below), whose sum is σ = 12628572. Its totient is φ = 12483072.

The previous prime is 12555817. The next prime is 12555833. The reversal of 12555821 is 12855521.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 6180196 + 6375625 = 2486^2 + 2525^2 .

It is a cyclic number.

It is not a de Polignac number, because 12555821 - 2² = 12555817 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 (12555121) 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, 36116 + ... + 36461.

It is an arithmetic number, because the mean of its divisors is an integer number (3157143).

Almost surely, 2^12555821 is an apocalyptic number.

It is an amenable number.

12555821 is a deficient number, since it is larger than the sum of its proper divisors (72751).

12555821 is an equidigital number, since it uses as much as digits as its factorization.

12555821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72750.

The product of its digits is 4000, while the sum is 29.

The square root of 12555821 is about 3543.4193937495. The cubic root of 12555821 is about 232.4243928822.

The spelling of 12555821 in words is "twelve million, five hundred fifty-five thousand, eight hundred twenty-one".