2778238681 has 3 divisors (see below), whose sum is σ = 2778291391. Its totient is φ = 2778185972.

The previous prime is 2778238637. The next prime is 2778238703. The reversal of 2778238681 is 1868328772.

The square root of 2778238681 is 52709.

It is a perfect power (a square), and thus also a powerful number.

2778238681 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 113614281 + 2664624400 = 10659^2 + 51620^2 .

It is not a de Polignac number, because 2778238681 - 2¹⁷ = 2778107609 is a prime.

It is a super-2 number, since 2×2778238681² = 15437220337209239522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2778298681) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 26355 + ... + 79063.

Almost surely, 2^2778238681 is an apocalyptic number.

2778238681 is the 52709-th square number.

2778238681 is the 26355-th centered octagonal number.

It is an amenable number.

2778238681 is a deficient number, since it is larger than the sum of its proper divisors (52710).

2778238681 is an frugal number, since it uses more digits than its factorization.

2778238681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 105418 (or 52709 counting only the distinct ones).

The product of its digits is 1806336, while the sum is 52.

The cubic root of 2778238681 is about 1405.7988527032.

Subtracting from 2778238681 its reverse (1868328772), we obtain a palindrome (909909909).

The spelling of 2778238681 in words is "two billion, seven hundred seventy-eight million, two hundred thirty-eight thousand, six hundred eighty-one".