2561312753661 has 4 divisors (see below), whose sum is σ = 3415083671552. Its totient is φ = 1707541835772.

The previous prime is 2561312753653. The next prime is 2561312753719. The reversal of 2561312753661 is 1663572131652.

It is a happy number.

2561312753661 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 2561312753661 - 2³ = 2561312753653 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 2561312753661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2561312753651) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 426885458941 + ... + 426885458946.

It is an arithmetic number, because the mean of its divisors is an integer number (853770917888).

Almost surely, 2^{2561312753661} is an apocalyptic number.

It is an amenable number.

2561312753661 is a deficient number, since it is larger than the sum of its proper divisors (853770917891).

2561312753661 is an equidigital number, since it uses as much as digits as its factorization.

2561312753661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 853770917890.

The product of its digits is 1360800, while the sum is 48.

The spelling of 2561312753661 in words is "two trillion, five hundred sixty-one billion, three hundred twelve million, seven hundred fifty-three thousand, six hundred sixty-one".