2661661663 has 4 divisors (see below), whose sum is σ = 2678615080. Its totient is φ = 2644708248.

The previous prime is 2661661609. The next prime is 2661661669. The reversal of 2661661663 is 3661661662.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 2661661663 - 2²⁹ = 2124790751 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 (2661661669) 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, 8476473 + ... + 8476786.

It is an arithmetic number, because the mean of its divisors is an integer number (669653770).

Almost surely, 2^2661661663 is an apocalyptic number.

2661661663 is a deficient number, since it is larger than the sum of its proper divisors (16953417).

2661661663 is a wasteful number, since it uses less digits than its factorization.

2661661663 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16953416.

The product of its digits is 279936, while the sum is 43.

The square root of 2661661663 is about 51591.2944497422. The cubic root of 2661661663 is about 1385.8544364313.

Subtracting 2661661663 from its reverse (3661661662), we obtain a palindrome (999999999).

The spelling of 2661661663 in words is "two billion, six hundred sixty-one million, six hundred sixty-one thousand, six hundred sixty-three".