663644665 has 4 divisors (see below), whose sum is σ = 796373604. Its totient is φ = 530915728.

The previous prime is 663644651. The next prime is 663644669. The reversal of 663644665 is 566446366.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 455737104 + 207907561 = 21348^2 + 14419^2 .

It is a cyclic number.

It is not a de Polignac number, because 663644665 - 2⁷ = 663644537 is a prime.

It is a super-3 number, since 3×663644665³ (a number of 27 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (663644669) 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, 66364462 + ... + 66364471.

It is an arithmetic number, because the mean of its divisors is an integer number (199093401).

Almost surely, 2^663644665 is an apocalyptic number.

It is an amenable number.

663644665 is a deficient number, since it is larger than the sum of its proper divisors (132728939).

663644665 is a wasteful number, since it uses less digits than its factorization.

663644665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 132728938.

The product of its digits is 1866240, while the sum is 46.

The square root of 663644665 is about 25761.3016945961. The cubic root of 663644665 is about 872.2584843960.

The spelling of 663644665 in words is "six hundred sixty-three million, six hundred forty-four thousand, six hundred sixty-five".