2821565 has 4 divisors (see below), whose sum is σ = 3385884. Its totient is φ = 2257248.

The previous prime is 2821549. The next prime is 2821573. The reversal of 2821565 is 5651282.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 574564 + 2247001 = 758^2 + 1499^2 .

It is a cyclic number.

It is not a de Polignac number, because 2821565 - 2⁴ = 2821549 is a prime.

It is a super-2 number, since 2×2821565² = 15922458098450, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

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, 282152 + ... + 282161.

It is an arithmetic number, because the mean of its divisors is an integer number (846471).

2^2821565 is an apocalyptic number.

It is an amenable number.

2821565 is a deficient number, since it is larger than the sum of its proper divisors (564319).

2821565 is an equidigital number, since it uses as much as digits as its factorization.

2821565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 564318.

The product of its digits is 4800, while the sum is 29.

The square root of 2821565 is about 1679.7514697121. The cubic root of 2821565 is about 141.3068948756.

It can be divided in two parts, 282 and 1565, that multiplied together give a triangular number (441330 = T₉₃₉).

The spelling of 2821565 in words is "two million, eight hundred twenty-one thousand, five hundred sixty-five".