2561971568647 has 2 divisors, whose sum is σ = 2561971568648. Its totient is φ = 2561971568646.

The previous prime is 2561971568621. The next prime is 2561971568659. The reversal of 2561971568647 is 7468651791652.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 2561971568647 - 2¹⁹ = 2561971044359 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2561971568677) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1280985784323 + 1280985784324.

It is an arithmetic number, because the mean of its divisors is an integer number (1280985784324).

Almost surely, 2^{2561971568647} is an apocalyptic number.

2561971568647 is a deficient number, since it is larger than the sum of its proper divisors (1).

2561971568647 is an equidigital number, since it uses as much as digits as its factorization.

2561971568647 is an evil number, because the sum of its binary digits is even.

The product of its digits is 152409600, while the sum is 67.

The spelling of 2561971568647 in words is "two trillion, five hundred sixty-one billion, nine hundred seventy-one million, five hundred sixty-eight thousand, six hundred forty-seven".