663644 has 12 divisors (see below), whose sum is σ = 1167768. Its totient is φ = 330000.

The previous prime is 663631. The next prime is 663653. The reversal of 663644 is 446366.

It is a congruent number.

It is an unprimeable number.

663644 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 674 + ... + 1334.

It is an arithmetic number, because the mean of its divisors is an integer number (97314).

2⁶⁶³⁶⁴⁴ is an apocalyptic number.

It is an amenable number.

663644 is a deficient number, since it is larger than the sum of its proper divisors (504124).

663644 is a wasteful number, since it uses less digits than its factorization.

663644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 916 (or 914 counting only the distinct ones).

The product of its digits is 10368, while the sum is 29.

The square root of 663644 is about 814.6434803029. The cubic root of 663644 is about 87.2258193049.

The spelling of 663644 in words is "six hundred sixty-three thousand, six hundred forty-four".