686637 has 30 divisors (see below), whose sum is σ = 1200078. Its totient is φ = 390096.

The previous prime is 686611. The next prime is 686639. The reversal of 686637 is 736686.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 670761 + 15876 = 819^2 + 126^2 .

It is not a de Polignac number, because 686637 - 2¹⁰ = 685613 is a prime.

It is a zygodrome in base 7.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (686639) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 29 ways as a sum of consecutive naturals, for example, 3883 + ... + 4055.

2⁶⁸⁶⁶³⁷ is an apocalyptic number.

It is an amenable number.

686637 is a deficient number, since it is larger than the sum of its proper divisors (513441).

686637 is a wasteful number, since it uses less digits than its factorization.

686637 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 199 (or 183 counting only the distinct ones).

The product of its digits is 36288, while the sum is 36.

The square root of 686637 is about 828.6356255919. The cubic root of 686637 is about 88.2217633369.

It can be divided in two parts, 6866 and 37, that added together give a triangular number (6903 = T₁₁₇).

The spelling of 686637 in words is "six hundred eighty-six thousand, six hundred thirty-seven".