663506 has 4 divisors (see below), whose sum is σ = 995262. Its totient is φ = 331752.

The previous prime is 663463. The next prime is 663517. The reversal of 663506 is 605366.

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

It can be written as a sum of positive squares in only one way, i.e., 654481 + 9025 = 809^2 + 95^2 .

It is a Curzon number.

It is an unprimeable number.

663506 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 (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 165875 + ... + 165878.

2⁶⁶³⁵⁰⁶ is an apocalyptic number.

663506 is a deficient number, since it is larger than the sum of its proper divisors (331756).

663506 is a wasteful number, since it uses less digits than its factorization.

663506 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 331755.

The product of its (nonzero) digits is 3240, while the sum is 26.

The square root of 663506 is about 814.5587762709. The cubic root of 663506 is about 87.2197728917.

The spelling of 663506 in words is "six hundred sixty-three thousand, five hundred six".