2856781 has 4 divisors (see below), whose sum is σ = 2883100. Its totient is φ = 2830464.

The previous prime is 2856779. The next prime is 2856803. The reversal of 2856781 is 1876582.

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 1522756 + 1334025 = 1234^2 + 1155^2 .

It is a cyclic number.

It is not a de Polignac number, because 2856781 - 2¹ = 2856779 is a prime.

It is a super-2 number, since 2×2856781² = 16322395363922, which contains 22 as substring.

It is a Duffinian number.

2856781 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 2856781.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2854781) 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, 12996 + ... + 13213.

It is an arithmetic number, because the mean of its divisors is an integer number (720775).

2^2856781 is an apocalyptic number.

It is an amenable number.

2856781 is a deficient number, since it is larger than the sum of its proper divisors (26319).

2856781 is a wasteful number, since it uses less digits than its factorization.

2856781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26318.

The product of its digits is 26880, while the sum is 37.

The square root of 2856781 is about 1690.2014672813. The cubic root of 2856781 is about 141.8923504692.

The spelling of 2856781 in words is "two million, eight hundred fifty-six thousand, seven hundred eighty-one".