2978809 has 4 divisors (see below), whose sum is σ = 3001680. Its totient is φ = 2955940.

The previous prime is 2978797. The next prime is 2978819. The reversal of 2978809 is 9088792.

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 2978809 - 2⁷ = 2978681 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2978819) 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, 11239 + ... + 11500.

It is an arithmetic number, because the mean of its divisors is an integer number (750420).

2^2978809 is an apocalyptic number.

It is an amenable number.

2978809 is a deficient number, since it is larger than the sum of its proper divisors (22871).

2978809 is a wasteful number, since it uses less digits than its factorization.

2978809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22870.

The product of its (nonzero) digits is 72576, while the sum is 43.

The square root of 2978809 is about 1725.9226518011. The cubic root of 2978809 is about 143.8845686310.

The spelling of 2978809 in words is "two million, nine hundred seventy-eight thousand, eight hundred nine".