663909 has 4 divisors (see below), whose sum is σ = 885216. Its totient is φ = 442604.

The previous prime is 663907. The next prime is 663937. The reversal of 663909 is 909366.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 663909 - 2¹ = 663907 is a prime.

It is a D-number.

663909 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 663909.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (663907) 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, 110649 + ... + 110654.

It is an arithmetic number, because the mean of its divisors is an integer number (221304).

2⁶⁶³⁹⁰⁹ is an apocalyptic number.

It is an amenable number.

663909 is a deficient number, since it is larger than the sum of its proper divisors (221307).

663909 is a wasteful number, since it uses less digits than its factorization.

663909 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 221306.

The product of its (nonzero) digits is 8748, while the sum is 33.

The square root of 663909 is about 814.8061119064. The cubic root of 663909 is about 87.2374278210.

The spelling of 663909 in words is "six hundred sixty-three thousand, nine hundred nine".