666555663 has 16 divisors (see below), whose sum is σ = 976193280. Its totient is φ = 402678144.

The previous prime is 666555649. The next prime is 666555667. The reversal of 666555663 is 366555666.

It is not a de Polignac number, because 666555663 - 2⁴ = 666555647 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666555667) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 252906 + ... + 255527.

It is an arithmetic number, because the mean of its divisors is an integer number (61012080).

Almost surely, 2^666555663 is an apocalyptic number.

666555663 is a deficient number, since it is larger than the sum of its proper divisors (309637617).

666555663 is a wasteful number, since it uses less digits than its factorization.

666555663 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 508478.

The product of its digits is 2916000, while the sum is 48.

The square root of 666555663 is about 25817.7393084677. The cubic root of 666555663 is about 873.5319767277.

The spelling of 666555663 in words is "six hundred sixty-six million, five hundred fifty-five thousand, six hundred sixty-three".