687640 has 16 divisors (see below), whose sum is σ = 1547280. Its totient is φ = 275040.

The previous prime is 687637. The next prime is 687641. The reversal of 687640 is 46786.

687640 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (687641) 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, 8556 + ... + 8635.

It is an arithmetic number, because the mean of its divisors is an integer number (96705).

2⁶⁸⁷⁶⁴⁰ is an apocalyptic number.

It is an amenable number.

687640 is an abundant number, since it is smaller than the sum of its proper divisors (859640).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

687640 is a wasteful number, since it uses less digits than its factorization.

687640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17202 (or 17198 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 31.

The square root of 687640 is about 829.2406164679. The cubic root of 687640 is about 88.2646988707.

The spelling of 687640 in words is "six hundred eighty-seven thousand, six hundred forty".