687645 has 48 divisors (see below), whose sum is σ = 1422720. Its totient is φ = 300672.

The previous prime is 687641. The next prime is 687647. The reversal of 687645 is 546786.

687645 = T₁₇₄ + T₁₇₅ + ... + T₂₁₀.

It is a happy number.

687645 is a `hidden beast` number, since 6 + 8 + 7 + 645 = 666.

It is not a de Polignac number, because 687645 - 2² = 687641 is a prime.

It is an Ulam number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 687645.

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 47 ways as a sum of consecutive naturals, for example, 11626 + ... + 11684.

It is an arithmetic number, because the mean of its divisors is an integer number (29640).

2⁶⁸⁷⁶⁴⁵ is an apocalyptic number.

It is an amenable number.

687645 is an abundant number, since it is smaller than the sum of its proper divisors (735075).

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

687645 is a wasteful number, since it uses less digits than its factorization.

687645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 114 (or 111 counting only the distinct ones).

The product of its digits is 40320, while the sum is 36.

The square root of 687645 is about 829.2436312689. The cubic root of 687645 is about 88.2649128016.

The spelling of 687645 in words is "six hundred eighty-seven thousand, six hundred forty-five".