665506663 has 4 divisors (see below), whose sum is σ = 665561680. Its totient is φ = 665451648.

The previous prime is 665506649. The next prime is 665506687. The reversal of 665506663 is 366605566.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 665506663 - 2⁹ = 665506151 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 (665506613) 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, 570 + ... + 36487.

It is an arithmetic number, because the mean of its divisors is an integer number (166390420).

Almost surely, 2^665506663 is an apocalyptic number.

665506663 is a deficient number, since it is larger than the sum of its proper divisors (55017).

665506663 is a wasteful number, since it uses less digits than its factorization.

665506663 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55016.

The product of its (nonzero) digits is 583200, while the sum is 43.

The square root of 665506663 is about 25797.4158201941. The cubic root of 665506663 is about 873.0734923065.

The spelling of 665506663 in words is "six hundred sixty-five million, five hundred six thousand, six hundred sixty-three".