2028821 has 4 divisors (see below), whose sum is σ = 2083692. Its totient is φ = 1973952.

The previous prime is 2028809. The next prime is 2028841. The reversal of 2028821 is 1288202.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1288202 = 2 ⋅644101.

It can be written as a sum of positive squares in 2 ways, for example, as 1473796 + 555025 = 1214^2 + 745^2 .

It is a cyclic number.

It is not a de Polignac number, because 2028821 - 2⁶ = 2028757 is a prime.

It is a super-2 number, since 2×2028821² = 8232229300082, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2028841) 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, 27380 + ... + 27453.

It is an arithmetic number, because the mean of its divisors is an integer number (520923).

2^2028821 is an apocalyptic number.

It is an amenable number.

2028821 is a deficient number, since it is larger than the sum of its proper divisors (54871).

2028821 is an equidigital number, since it uses as much as digits as its factorization.

2028821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 54870.

The product of its (nonzero) digits is 512, while the sum is 23.

The square root of 2028821 is about 1424.3668768965. The cubic root of 2028821 is about 126.5944240253.

The spelling of 2028821 in words is "two million, twenty-eight thousand, eight hundred twenty-one".