2688768661 has 4 divisors (see below), whose sum is σ = 2689302924. Its totient is φ = 2688234400.

The previous prime is 2688768659. The next prime is 2688768673. The reversal of 2688768661 is 1668678862.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1668678862 = 2 ⋅834339431.

It can be written as a sum of positive squares in 2 ways, for example, as 1356080625 + 1332688036 = 36825^2 + 36506^2 .

It is a cyclic number.

It is not a de Polignac number, because 2688768661 - 2¹ = 2688768659 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2688768596 and 2688768605.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2688768961) 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 3 ways as a sum of consecutive naturals, for example, 259510 + ... + 269671.

It is an arithmetic number, because the mean of its divisors is an integer number (672325731).

Almost surely, 2^2688768661 is an apocalyptic number.

It is an amenable number.

2688768661 is a deficient number, since it is larger than the sum of its proper divisors (534263).

2688768661 is an equidigital number, since it uses as much as digits as its factorization.

2688768661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 534262.

The product of its digits is 9289728, while the sum is 58.

The square root of 2688768661 is about 51853.3379928429. The cubic root of 2688768661 is about 1390.5431793570.

The spelling of 2688768661 in words is "two billion, six hundred eighty-eight million, seven hundred sixty-eight thousand, six hundred sixty-one".