687634 has 4 divisors (see below), whose sum is σ = 1031454. Its totient is φ = 343816.

The previous prime is 687623. The next prime is 687637. The reversal of 687634 is 436786.

687634 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 664225 + 23409 = 815^2 + 153^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 687634.

It is not an unprimeable number, because it can be changed into a prime (687637) by changing a digit.

687634 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 171907 + ... + 171910.

2⁶⁸⁷⁶³⁴ is an apocalyptic number.

687634 is a deficient number, since it is larger than the sum of its proper divisors (343820).

687634 is a wasteful number, since it uses less digits than its factorization.

687634 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 343819.

The product of its digits is 24192, while the sum is 34.

The square root of 687634 is about 829.2369986922. The cubic root of 687634 is about 88.2644421522.

The spelling of 687634 in words is "six hundred eighty-seven thousand, six hundred thirty-four".