2778431645 has 18 divisors (see below), whose sum is σ = 3666485214. Its totient is φ = 2019734640.

The previous prime is 2778431629. The next prime is 2778431653. The reversal of 2778431645 is 5461348772.

It can be written as a sum of positive squares in only one way, i.e., 2222745316 + 555686329 = 47146^2 + 23573^2 .

It is not a de Polignac number, because 2778431645 - 2⁴ = 2778431629 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 2778431645.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 1295444 + ... + 1297586.

It is an arithmetic number, because the mean of its divisors is an integer number (203693623).

Almost surely, 2^2778431645 is an apocalyptic number.

It is an amenable number.

2778431645 is a deficient number, since it is larger than the sum of its proper divisors (888053569).

2778431645 is an frugal number, since it uses more digits than its factorization.

2778431645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4313 (or 2159 counting only the distinct ones).

The product of its digits is 1128960, while the sum is 47.

The square root of 2778431645 is about 52710.8304336025. The cubic root of 2778431645 is about 1405.8313987777.

The spelling of 2778431645 in words is "two billion, seven hundred seventy-eight million, four hundred thirty-one thousand, six hundred forty-five".