685531 has 16 divisors (see below), whose sum is σ = 887040. Its totient is φ = 514080.

The previous prime is 685519. The next prime is 685537. The reversal of 685531 is 135586.

It is not a de Polignac number, because 685531 - 2⁹ = 685019 is a prime.

It is a super-2 number, since 2×685531² = 939905503922, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 685531.

It is not an unprimeable number, because it can be changed into a prime (685537) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2080 + ... + 2386.

It is an arithmetic number, because the mean of its divisors is an integer number (55440).

2⁶⁸⁵⁵³¹ is an apocalyptic number.

685531 is a deficient number, since it is larger than the sum of its proper divisors (201509).

685531 is a wasteful number, since it uses less digits than its factorization.

685531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 354.

The product of its digits is 3600, while the sum is 28.

The square root of 685531 is about 827.9679945505. The cubic root of 685531 is about 88.1743701700.

Subtracting from 685531 its reverse (135586), we obtain a palindrome (549945).

It can be divided in two parts, 6855 and 31, that added together give a palindrome (6886).

The spelling of 685531 in words is "six hundred eighty-five thousand, five hundred thirty-one".