2820821 has 2 divisors, whose sum is σ = 2820822. Its totient is φ = 2820820.

The previous prime is 2820817. The next prime is 2820833. The reversal of 2820821 is 1280282.

2820821 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 2739025 + 81796 = 1655^2 + 286^2 .

It is a cyclic number.

It is not a de Polignac number, because 2820821 - 2² = 2820817 is a prime.

It is a super-2 number, since 2×2820821² = 15914062228082, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2825821) 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 as a sum of consecutive naturals, namely, 1410410 + 1410411.

It is an arithmetic number, because the mean of its divisors is an integer number (1410411).

2^2820821 is an apocalyptic number.

It is an amenable number.

2820821 is a deficient number, since it is larger than the sum of its proper divisors (1).

2820821 is an equidigital number, since it uses as much as digits as its factorization.

2820821 is an odious number, because the sum of its binary digits is odd.

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

The square root of 2820821 is about 1679.5299937780. The cubic root of 2820821 is about 141.2944736872.

The spelling of 2820821 in words is "two million, eight hundred twenty thousand, eight hundred twenty-one".