2840809 has 4 divisors (see below), whose sum is σ = 2932480. Its totient is φ = 2749140.

The previous prime is 2840801. The next prime is 2840857. The reversal of 2840809 is 9080482.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 2840809 - 2³ = 2840801 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (31), and also a Moran number because the ratio is a prime number: 91639 = 2840809 / (2 + 8 + 4 + 0 + 8 + 0 + 9).

It is a Duffinian number.

2840809 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (2840801) 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, 45789 + ... + 45850.

It is an arithmetic number, because the mean of its divisors is an integer number (733120).

2^2840809 is an apocalyptic number.

It is an amenable number.

2840809 is a deficient number, since it is larger than the sum of its proper divisors (91671).

2840809 is an equidigital number, since it uses as much as digits as its factorization.

2840809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91670.

The product of its (nonzero) digits is 4608, while the sum is 31.

The square root of 2840809 is about 1685.4699641346. The cubic root of 2840809 is about 141.6274204242.

It can be divided in two parts, 284080 and 9, that added together give a square (284089 = 533²).

The spelling of 2840809 in words is "two million, eight hundred forty thousand, eight hundred nine".