663994 has 4 divisors (see below), whose sum is σ = 995994. Its totient is φ = 331996.

The previous prime is 663991. The next prime is 663997. The reversal of 663994 is 499366.

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

It is an interprime number because it is at equal distance from previous prime (663991) and next prime (663997).

It can be written as a sum of positive squares in only one way, i.e., 660969 + 3025 = 813^2 + 55^2 .

It is not an unprimeable number, because it can be changed into a prime (663991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 165997 + ... + 166000.

2⁶⁶³⁹⁹⁴ is an apocalyptic number.

663994 is a deficient number, since it is larger than the sum of its proper divisors (332000).

663994 is a wasteful number, since it uses less digits than its factorization.

663994 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 331999.

The product of its digits is 34992, while the sum is 37.

The square root of 663994 is about 814.8582698850. The cubic root of 663994 is about 87.2411506530.

It can be divided in two parts, 6 and 63994, that added together give a cube (64000 = 40³).

The spelling of 663994 in words is "six hundred sixty-three thousand, nine hundred ninety-four".