2566617681 has 4 divisors (see below), whose sum is σ = 3422156912. Its totient is φ = 1711078452.

The previous prime is 2566617673. The next prime is 2566617701. The reversal of 2566617681 is 1867166652.

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 2566617681 - 2³ = 2566617673 is a prime.

It is a super-2 number, since 2×2566617681² = 13175052640843635522, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 2566617681.

It is not an unprimeable number, because it can be changed into a prime (2566617661) 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, 427769611 + ... + 427769616.

It is an arithmetic number, because the mean of its divisors is an integer number (855539228).

Almost surely, 2^2566617681 is an apocalyptic number.

It is an amenable number.

2566617681 is a deficient number, since it is larger than the sum of its proper divisors (855539231).

2566617681 is an equidigital number, since it uses as much as digits as its factorization.

2566617681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 855539230.

The product of its digits is 725760, while the sum is 48.

The square root of 2566617681 is about 50661.7970565593. The cubic root of 2566617681 is about 1369.1585009359.

The spelling of 2566617681 in words is "two billion, five hundred sixty-six million, six hundred seventeen thousand, six hundred eighty-one".