2560321661 has 4 divisors (see below), whose sum is σ = 2560440000. Its totient is φ = 2560203324.

The previous prime is 2560321633. The next prime is 2560321691. The reversal of 2560321661 is 1661230652.

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, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 2560321661 - 2¹⁸ = 2560059517 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2560321691) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16421 + ... + 73418.

It is an arithmetic number, because the mean of its divisors is an integer number (640110000).

Almost surely, 2^2560321661 is an apocalyptic number.

It is an amenable number.

2560321661 is a deficient number, since it is larger than the sum of its proper divisors (118339).

2560321661 is an equidigital number, since it uses as much as digits as its factorization.

2560321661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 118338.

The product of its (nonzero) digits is 12960, while the sum is 32.

The square root of 2560321661 is about 50599.6211547083. The cubic root of 2560321661 is about 1368.0380500015.

The spelling of 2560321661 in words is "two billion, five hundred sixty million, three hundred twenty-one thousand, six hundred sixty-one".