2821821 has 4 divisors (see below), whose sum is σ = 3762432. Its totient is φ = 1881212.

The previous prime is 2821817. The next prime is 2821829. The reversal of 2821821 is 1281282.

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 2821821 - 2² = 2821817 is a prime.

It is a D-number.

It is a junction number, because it is equal to n+sod(n) for n = 2821791 and 2821800.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2821829) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 470301 + ... + 470306.

It is an arithmetic number, because the mean of its divisors is an integer number (940608).

2^2821821 is an apocalyptic number.

It is an amenable number.

2821821 is a deficient number, since it is larger than the sum of its proper divisors (940611).

2821821 is an equidigital number, since it uses as much as digits as its factorization.

2821821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 940610.

The product of its digits is 512, while the sum is 24.

The square root of 2821821 is about 1679.8276697328. The cubic root of 2821821 is about 141.3111683280.

The spelling of 2821821 in words is "two million, eight hundred twenty-one thousand, eight hundred twenty-one".