2561856226065 has 48 divisors (see below), whose sum is σ = 4501703203920. Its totient is φ = 1347509882880.

The previous prime is 2561856226031. The next prime is 2561856226079. The reversal of 2561856226065 is 5606226581652.

2561856226065 is a `hidden beast` number, since 2 + 5 + 6 + 1 + 8 + 5 + 6 + 22 + 606 + 5 = 666.

It can be written as a sum of positive squares in 8 ways, for example, as 519835232016 + 2042020994049 = 720996^2 + 1428993^2 .

It is not a de Polignac number, because 2561856226065 - 2⁷ = 2561856225937 is a prime.

It is an unprimeable number.

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 47 ways as a sum of consecutive naturals, for example, 86449671 + ... + 86479299.

It is an arithmetic number, because the mean of its divisors is an integer number (93785483415).

Almost surely, 2^{2561856226065} is an apocalyptic number.

It is an amenable number.

2561856226065 is a deficient number, since it is larger than the sum of its proper divisors (1939846977855).

2561856226065 is a wasteful number, since it uses less digits than its factorization.

2561856226065 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 56034 (or 56031 counting only the distinct ones).

The product of its (nonzero) digits is 10368000, while the sum is 54.

The spelling of 2561856226065 in words is "two trillion, five hundred sixty-one billion, eight hundred fifty-six million, two hundred twenty-six thousand, sixty-five".