663440 has 20 divisors (see below), whose sum is σ = 1542684. Its totient is φ = 265344.

The previous prime is 663437. The next prime is 663463. The reversal of 663440 is 44366.

It can be written as a sum of positive squares in 2 ways, for example, as 190096 + 473344 = 436^2 + 688^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a super-5 number, since 5×663440⁵ (a number of 30 digits) contains 55555 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4067 + ... + 4226.

2⁶⁶³⁴⁴⁰ is an apocalyptic number.

It is an amenable number.

663440 is an abundant number, since it is smaller than the sum of its proper divisors (879244).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

663440 is a wasteful number, since it uses less digits than its factorization.

663440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8306 (or 8300 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 23.

The square root of 663440 is about 814.5182625331. The cubic root of 663440 is about 87.2168808325.

The spelling of 663440 in words is "six hundred sixty-three thousand, four hundred forty".