12621821 has 4 divisors (see below), whose sum is σ = 12654012. Its totient is φ = 12589632.

The previous prime is 12621799. The next prime is 12621823. The reversal of 12621821 is 12812621.

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 8916196 + 3705625 = 2986^2 + 1925^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-12621821 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12621823) 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, 15500 + ... + 16293.

It is an arithmetic number, because the mean of its divisors is an integer number (3163503).

Almost surely, 2^12621821 is an apocalyptic number.

It is an amenable number.

12621821 is a deficient number, since it is larger than the sum of its proper divisors (32191).

12621821 is an equidigital number, since it uses as much as digits as its factorization.

12621821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32190.

The product of its digits is 384, while the sum is 23.

The square root of 12621821 is about 3552.7202254048. The cubic root of 12621821 is about 232.8309296793.

The spelling of 12621821 in words is "twelve million, six hundred twenty-one thousand, eight hundred twenty-one".