661818308718663 has 12 divisors (see below), whose sum is σ = 958714706582568. Its totient is φ = 439940700894480.

The previous prime is 661818308718661. The next prime is 661818308718673. The reversal of 661818308718663 is 366817803818166.

661818308718663 is a `hidden beast` number, since 6 + 6 + 1 + 81 + 8 + 308 + 7 + 186 + 63 = 666.

661818308718663 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 661818308718663 - 2¹ = 661818308718661 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 661818308718591 and 661818308718600.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661818308718661) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 105958739868 + ... + 105958746113.

It is an arithmetic number, because the mean of its divisors is an integer number (79892892215214).

Almost surely, 2^{661818308718663} is an apocalyptic number.

661818308718663 is a deficient number, since it is larger than the sum of its proper divisors (296896397863905).

661818308718663 is a wasteful number, since it uses less digits than its factorization.

661818308718663 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 211917486334 (or 211917486331 counting only the distinct ones).

The product of its (nonzero) digits is 334430208, while the sum is 72.

The spelling of 661818308718663 in words is "six hundred sixty-one trillion, eight hundred eighteen billion, three hundred eight million, seven hundred eighteen thousand, six hundred sixty-three".