663987 has 8 divisors (see below), whose sum is σ = 923904. Its totient is φ = 423368.

The previous prime is 663983. The next prime is 663991. The reversal of 663987 is 789366.

It is an interprime number because it is at equal distance from previous prime (663983) and next prime (663991).

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 663987 - 2² = 663983 is a prime.

It is not an unprimeable number, because it can be changed into a prime (663983) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4743 + ... + 4880.

It is an arithmetic number, because the mean of its divisors is an integer number (115488).

2⁶⁶³⁹⁸⁷ is an apocalyptic number.

663987 is a deficient number, since it is larger than the sum of its proper divisors (259917).

663987 is a wasteful number, since it uses less digits than its factorization.

663987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9649.

The product of its digits is 54432, while the sum is 39.

The square root of 663987 is about 814.8539746482. The cubic root of 663987 is about 87.2408440788.

The spelling of 663987 in words is "six hundred sixty-three thousand, nine hundred eighty-seven".