687591 has 12 divisors (see below), whose sum is σ = 1045720. Its totient is φ = 434160.

The previous prime is 687581. The next prime is 687593. The reversal of 687591 is 195786.

687591 is a `hidden beast` number, since 68 + 7 + 591 = 666.

It is not a de Polignac number, because 687591 - 2⁵ = 687559 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (687593) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1840 + ... + 2181.

2⁶⁸⁷⁵⁹¹ is an apocalyptic number.

687591 is a deficient number, since it is larger than the sum of its proper divisors (358129).

687591 is a wasteful number, since it uses less digits than its factorization.

687591 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4046 (or 4043 counting only the distinct ones).

The product of its digits is 15120, while the sum is 36.

The square root of 687591 is about 829.2110708378. The cubic root of 687591 is about 88.2626022925.

The spelling of 687591 in words is "six hundred eighty-seven thousand, five hundred ninety-one".