685669 has 2 divisors, whose sum is σ = 685670. Its totient is φ = 685668.

The previous prime is 685649. The next prime is 685679. The reversal of 685669 is 966586.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 422500 + 263169 = 650^2 + 513^2 .

It is a cyclic number.

It is not a de Polignac number, because 685669 - 2⁵ = 685637 is a prime.

It is a super-2 number, since 2×685669² = 940283955122, which contains 22 as substring.

It is a nialpdrome in base 16.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (685609) 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 as a sum of consecutive naturals, namely, 342834 + 342835.

It is an arithmetic number, because the mean of its divisors is an integer number (342835).

2⁶⁸⁵⁶⁶⁹ is an apocalyptic number.

It is an amenable number.

685669 is a deficient number, since it is larger than the sum of its proper divisors (1).

685669 is an equidigital number, since it uses as much as digits as its factorization.

685669 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 77760, while the sum is 40.

The square root of 685669 is about 828.0513269116. The cubic root of 685669 is about 88.1802863852.

The spelling of 685669 in words is "six hundred eighty-five thousand, six hundred sixty-nine".