663661665 has 48 divisors (see below), whose sum is σ = 1241809920. Its totient is φ = 326874240.

The previous prime is 663661643. The next prime is 663661693. The reversal of 663661665 is 566166366.

663661665 is a `hidden beast` number, since 6 + 636 + 6 + 1 + 6 + 6 + 5 = 666.

663661665 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 663661665 - 2⁸ = 663661409 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 663661665.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 18960 + ... + 41070.

It is an arithmetic number, because the mean of its divisors is an integer number (25871040).

Almost surely, 2^663661665 is an apocalyptic number.

It is an amenable number.

663661665 is a deficient number, since it is larger than the sum of its proper divisors (578148255).

663661665 is a wasteful number, since it uses less digits than its factorization.

663661665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22174 (or 22171 counting only the distinct ones).

The product of its digits is 699840, while the sum is 45.

The square root of 663661665 is about 25761.6316447542. The cubic root of 663661665 is about 872.2659322911.

The spelling of 663661665 in words is "six hundred sixty-three million, six hundred sixty-one thousand, six hundred sixty-five".