2778309 has 6 divisors (see below), whose sum is σ = 4013126. Its totient is φ = 1852200.

The previous prime is 2778299. The next prime is 2778323. The reversal of 2778309 is 9038772.

It can be written as a sum of positive squares in only one way, i.e., 2772225 + 6084 = 1665^2 + 78^2 .

It is not a de Polignac number, because 2778309 - 2⁵ = 2778277 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2778329) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 154342 + ... + 154359.

2^2778309 is an apocalyptic number.

It is an amenable number.

2778309 is a deficient number, since it is larger than the sum of its proper divisors (1234817).

2778309 is a wasteful number, since it uses less digits than its factorization.

2778309 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 308707 (or 308704 counting only the distinct ones).

The product of its (nonzero) digits is 21168, while the sum is 36.

The square root of 2778309 is about 1666.8260257147. The cubic root of 2778309 is about 140.5810713159.

The spelling of 2778309 in words is "two million, seven hundred seventy-eight thousand, three hundred nine".