2566821 has 4 divisors (see below), whose sum is σ = 3422432. Its totient is φ = 1711212.

The previous prime is 2566807. The next prime is 2566829. The reversal of 2566821 is 1286652.

2566821 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 not a de Polignac number, because 2566821 - 2⁶ = 2566757 is a prime.

It is a D-number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2566829) 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, 427801 + ... + 427806.

It is an arithmetic number, because the mean of its divisors is an integer number (855608).

2^2566821 is an apocalyptic number.

It is an amenable number.

2566821 is a deficient number, since it is larger than the sum of its proper divisors (855611).

2566821 is an equidigital number, since it uses as much as digits as its factorization.

2566821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 855610.

The product of its digits is 5760, while the sum is 30.

The square root of 2566821 is about 1602.1301445263. The cubic root of 2566821 is about 136.9194653390.

The spelling of 2566821 in words is "two million, five hundred sixty-six thousand, eight hundred twenty-one".