2778216817 has 8 divisors (see below), whose sum is σ = 2854095336. Its totient is φ = 2702380032.

The previous prime is 2778216811. The next prime is 2778216929. The reversal of 2778216817 is 7186128772.

It can be written as a sum of positive squares in 4 ways, for example, as 1485023296 + 1293193521 = 38536^2 + 35961^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 2778216817 - 2³ = 2778216809 is a prime.

It is a super-2 number, since 2×2778216817² = 15436977364523222978, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2778216811) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 163473 + ... + 179665.

It is an arithmetic number, because the mean of its divisors is an integer number (356761917).

Almost surely, 2^2778216817 is an apocalyptic number.

It is an amenable number.

2778216817 is a deficient number, since it is larger than the sum of its proper divisors (75878519).

2778216817 is a wasteful number, since it uses less digits than its factorization.

2778216817 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20867.

The product of its digits is 526848, while the sum is 49.

The square root of 2778216817 is about 52708.7925966816. The cubic root of 2778216817 is about 1405.7951649390.

The spelling of 2778216817 in words is "two billion, seven hundred seventy-eight million, two hundred sixteen thousand, eight hundred seventeen".