663666623 has 4 divisors (see below), whose sum is σ = 663854928. Its totient is φ = 663478320.

The previous prime is 663666571. The next prime is 663666659. The reversal of 663666623 is 326666366.

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 663666623 - 2⁶ = 663666559 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 (663696623) 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, 88763 + ... + 95948.

It is an arithmetic number, because the mean of its divisors is an integer number (165963732).

Almost surely, 2^663666623 is an apocalyptic number.

663666623 is a deficient number, since it is larger than the sum of its proper divisors (188305).

663666623 is a wasteful number, since it uses less digits than its factorization.

663666623 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 188304.

The product of its digits is 839808, while the sum is 44.

The square root of 663666623 is about 25761.7278729514. The cubic root of 663666623 is about 872.2681044239.

The spelling of 663666623 in words is "six hundred sixty-three million, six hundred sixty-six thousand, six hundred twenty-three".