2561278694 has 16 divisors (see below), whose sum is σ = 4138295280. Its totient is φ = 1181887200.

The previous prime is 2561278673. The next prime is 2561278697. The reversal of 2561278694 is 4968721652.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2561278697) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 213044 + ... + 224744.

It is an arithmetic number, because the mean of its divisors is an integer number (258643455).

Almost surely, 2^2561278694 is an apocalyptic number.

2561278694 is a deficient number, since it is larger than the sum of its proper divisors (1577016586).

2561278694 is a wasteful number, since it uses less digits than its factorization.

2561278694 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20135.

The product of its digits is 1451520, while the sum is 50.

The square root of 2561278694 is about 50609.0771897690. The cubic root of 2561278694 is about 1368.2084835948.

The spelling of 2561278694 in words is "two billion, five hundred sixty-one million, two hundred seventy-eight thousand, six hundred ninety-four".