666687 has 16 divisors (see below), whose sum is σ = 1036800. Its totient is φ = 373152.

The previous prime is 666683. The next prime is 666697. The reversal of 666687 is 786666.

It is not a de Polignac number, because 666687 - 2² = 666683 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666683) by changing a digit.

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 in 15 ways as a sum of consecutive naturals, for example, 814 + ... + 1412.

It is an arithmetic number, because the mean of its divisors is an integer number (64800).

2⁶⁶⁶⁶⁸⁷ is an apocalyptic number.

666687 is a deficient number, since it is larger than the sum of its proper divisors (370113).

666687 is a wasteful number, since it uses less digits than its factorization.

666687 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 662.

The product of its digits is 72576, while the sum is 39.

The square root of 666687 is about 816.5090324056. The cubic root of 666687 is about 87.3589346047.

The spelling of 666687 in words is "six hundred sixty-six thousand, six hundred eighty-seven".