2555821 has 4 divisors (see below), whose sum is σ = 2599200. Its totient is φ = 2512444.

The previous prime is 2555809. The next prime is 2555837. The reversal of 2555821 is 1285552.

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 a cyclic number.

It is not a de Polignac number, because 2555821 - 2⁹ = 2555309 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 2555821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2555881) 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, 21601 + ... + 21718.

It is an arithmetic number, because the mean of its divisors is an integer number (649800).

2^2555821 is an apocalyptic number.

It is an amenable number.

2555821 is a deficient number, since it is larger than the sum of its proper divisors (43379).

2555821 is an equidigital number, since it uses as much as digits as its factorization.

2555821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43378.

The product of its digits is 4000, while the sum is 28.

The square root of 2555821 is about 1598.6935291043. The cubic root of 2555821 is about 136.7235978025.

The spelling of 2555821 in words is "two million, five hundred fifty-five thousand, eight hundred twenty-one".