2561971568640 has 960 divisors, whose sum is σ = 9576260080128. Its totient is φ = 577975091200.

The previous prime is 2561971568621. The next prime is 2561971568647. The reversal of 2561971568640 is 468651791652.

It is a tau number, because it is divible by the number of its divisors (960).

It is a Harshad number since it is a multiple of its sum of digits (60).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2561971568647) 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 63 ways as a sum of consecutive naturals, for example, 4917411580 + ... + 4917412100.

Almost surely, 2^{2561971568640} is an apocalyptic number.

2561971568640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 2561971568640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (4788130040064).

2561971568640 is an abundant number, since it is smaller than the sum of its proper divisors (7014288511488).

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

2561971568640 is a wasteful number, since it uses less digits than its factorization.

2561971568640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 692 (or 666 counting only the distinct ones).

The product of its (nonzero) digits is 21772800, while the sum is 60.

The spelling of 2561971568640 in words is "two trillion, five hundred sixty-one billion, nine hundred seventy-one million, five hundred sixty-eight thousand, six hundred forty".