686739 has 4 divisors (see below), whose sum is σ = 915656. Its totient is φ = 457824.

The previous prime is 686737. The next prime is 686761. The reversal of 686739 is 937686.

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

It is not a de Polignac number, because 686739 - 2¹ = 686737 is a prime.

It is a super-2 number, since 2×686739² = 943220908242, which contains 22 as substring.

It is a D-number.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 686697 and 686706.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (686731) 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 3 ways as a sum of consecutive naturals, for example, 114454 + ... + 114459.

It is an arithmetic number, because the mean of its divisors is an integer number (228914).

2⁶⁸⁶⁷³⁹ is an apocalyptic number.

686739 is a deficient number, since it is larger than the sum of its proper divisors (228917).

686739 is a wasteful number, since it uses less digits than its factorization.

686739 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 228916.

The product of its digits is 54432, while the sum is 39.

The square root of 686739 is about 828.6971702619. The cubic root of 686739 is about 88.2261315714.

The spelling of 686739 in words is "six hundred eighty-six thousand, seven hundred thirty-nine".