2809865 has 4 divisors (see below), whose sum is σ = 3371844. Its totient is φ = 2247888.

The previous prime is 2809847. The next prime is 2809867. The reversal of 2809865 is 5689082.

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 1301881 + 1507984 = 1141^2 + 1228^2 .

It is a cyclic number.

It is not a de Polignac number, because 2809865 - 2¹⁴ = 2793481 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2809867) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 280982 + ... + 280991.

It is an arithmetic number, because the mean of its divisors is an integer number (842961).

2^2809865 is an apocalyptic number.

It is an amenable number.

2809865 is a deficient number, since it is larger than the sum of its proper divisors (561979).

2809865 is an equidigital number, since it uses as much as digits as its factorization.

2809865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 561978.

The product of its (nonzero) digits is 34560, while the sum is 38.

The square root of 2809865 is about 1676.2651938163. The cubic root of 2809865 is about 141.1113082483. Note that the first 3 decimals are identical.

The spelling of 2809865 in words is "two million, eight hundred nine thousand, eight hundred sixty-five".