666663 has 8 divisors (see below), whose sum is σ = 892800. Its totient is φ = 442488.

The previous prime is 666649. The next prime is 666667. The reversal of 666663 is 366666.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 666663 - 2⁴ = 666647 is a prime.

It is a nialpdrome in base 10.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 666663.

It is not an unprimeable number, because it can be changed into a prime (666667) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 768 + ... + 1386.

It is an arithmetic number, because the mean of its divisors is an integer number (111600).

2⁶⁶⁶⁶⁶³ is an apocalyptic number.

666663 is a deficient number, since it is larger than the sum of its proper divisors (226137).

666663 is a wasteful number, since it uses less digits than its factorization.

666663 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 981.

The product of its digits is 23328, while the sum is 33.

The square root of 666663 is about 816.4943355590. The cubic root of 666663 is about 87.3578863169.

The spelling of 666663 in words is "six hundred sixty-six thousand, six hundred sixty-three".