2561736636 has 36 divisors (see below), whose sum is σ = 6816318600. Its totient is φ = 808969248.

The previous prime is 2561736623. The next prime is 2561736637. The reversal of 2561736636 is 6366371652.

2561736636 is a `hidden beast` number, since 2 + 5 + 6 + 1 + 7 + 3 + 6 + 636 = 666.

It is a tau number, because it is divible by the number of its divisors (36).

It is a junction number, because it is equal to n+sod(n) for n = 2561736591 and 2561736600.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2561736637) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1871931 + ... + 1873298.

Almost surely, 2^2561736636 is an apocalyptic number.

It is an amenable number.

2561736636 is an abundant number, since it is smaller than the sum of its proper divisors (4254581964).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

2561736636 is a wasteful number, since it uses less digits than its factorization.

2561736636 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3745258 (or 3745253 counting only the distinct ones).

The product of its digits is 816480, while the sum is 45.

The square root of 2561736636 is about 50613.6012945137. The cubic root of 2561736636 is about 1368.2900213560.

The spelling of 2561736636 in words is "two billion, five hundred sixty-one million, seven hundred thirty-six thousand, six hundred thirty-six".