691686 has 16 divisors (see below), whose sum is σ = 1537200. Its totient is φ = 230544.

The previous prime is 691681. The next prime is 691687. The reversal of 691686 is 686196.

It is a self number, because there is not a number n which added to its sum of digits gives 691686.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (691681) 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 7 ways as a sum of consecutive naturals, for example, 6351 + ... + 6458.

It is an arithmetic number, because the mean of its divisors is an integer number (96075).

2⁶⁹¹⁶⁸⁶ is an apocalyptic number.

691686 is an abundant number, since it is smaller than the sum of its proper divisors (845514).

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

691686 is a wasteful number, since it uses less digits than its factorization.

691686 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12820 (or 12814 counting only the distinct ones).

The product of its digits is 15552, while the sum is 36.

The square root of 691686 is about 831.6766198469. The cubic root of 691686 is about 88.4374737896.

The spelling of 691686 in words is "six hundred ninety-one thousand, six hundred eighty-six".