2806721 has 4 divisors (see below), whose sum is σ = 2859732. Its totient is φ = 2753712.

The previous prime is 2806711. The next prime is 2806757. The reversal of 2806721 is 1276082.

2806721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 790321 + 2016400 = 889^2 + 1420^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2806721 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2806711) 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 in 3 ways as a sum of consecutive naturals, for example, 26426 + ... + 26531.

It is an arithmetic number, because the mean of its divisors is an integer number (714933).

2^2806721 is an apocalyptic number.

2806721 is the 896-th centered heptagonal number.

It is an amenable number.

2806721 is a deficient number, since it is larger than the sum of its proper divisors (53011).

2806721 is an equidigital number, since it uses as much as digits as its factorization.

2806721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53010.

The product of its (nonzero) digits is 1344, while the sum is 26.

The square root of 2806721 is about 1675.3271322342. The cubic root of 2806721 is about 141.0586580882.

The spelling of 2806721 in words is "two million, eight hundred six thousand, seven hundred twenty-one".