2705821 has 2 divisors, whose sum is σ = 2705822. Its totient is φ = 2705820.

The previous prime is 2705819. The next prime is 2705827. The reversal of 2705821 is 1285072.

2705821 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., 2088025 + 617796 = 1445^2 + 786^2 .

It is a cyclic number.

It is not a de Polignac number, because 2705821 - 2¹ = 2705819 is a prime.

Together with 2705819, it forms a pair of twin primes.

2705821 is a lucky number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2705827) 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, 1352910 + 1352911.

It is an arithmetic number, because the mean of its divisors is an integer number (1352911).

2^2705821 is an apocalyptic number.

It is an amenable number.

2705821 is a deficient number, since it is larger than the sum of its proper divisors (1).

2705821 is an equidigital number, since it uses as much as digits as its factorization.

2705821 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1120, while the sum is 25.

The square root of 2705821 is about 1644.9379927523. The cubic root of 2705821 is about 139.3476623975.

The spelling of 2705821 in words is "two million, seven hundred five thousand, eight hundred twenty-one".