2561971568639 has 16 divisors (see below), whose sum is σ = 2977288177920. Its totient is φ = 2159235912960.

The previous prime is 2561971568621. The next prime is 2561971568647. The reversal of 2561971568639 is 9368651791652.

It is not a de Polignac number, because 2561971568639 - 2⁸ = 2561971568383 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2561971568609) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10326674 + ... + 10571855.

It is an arithmetic number, because the mean of its divisors is an integer number (186080511120).

Almost surely, 2^{2561971568639} is an apocalyptic number.

2561971568639 is a deficient number, since it is larger than the sum of its proper divisors (415316609281).

2561971568639 is a wasteful number, since it uses less digits than its factorization.

2561971568639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20898830.

The product of its digits is 146966400, while the sum is 68.

The spelling of 2561971568639 in words is "two trillion, five hundred sixty-one billion, nine hundred seventy-one million, five hundred sixty-eight thousand, six hundred thirty-nine".