687664 has 10 divisors (see below), whose sum is σ = 1332380. Its totient is φ = 343824.

The previous prime is 687647. The next prime is 687679. The reversal of 687664 is 466786.

687664 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an Ulam number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21474 + ... + 21505.

It is an arithmetic number, because the mean of its divisors is an integer number (133238).

2⁶⁸⁷⁶⁶⁴ is an apocalyptic number.

It is an amenable number.

687664 is a deficient number, since it is larger than the sum of its proper divisors (644716).

687664 is a wasteful number, since it uses less digits than its factorization.

687664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42987 (or 42981 counting only the distinct ones).

The product of its digits is 48384, while the sum is 37.

The square root of 687664 is about 829.2550874128. The cubic root of 687664 is about 88.2657257298.

The spelling of 687664 in words is "six hundred eighty-seven thousand, six hundred sixty-four".