685551 has 4 divisors (see below), whose sum is σ = 914072. Its totient is φ = 457032.

The previous prime is 685547. The next prime is 685591. The reversal of 685551 is 155586.

It is a happy number.

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

It is not a de Polignac number, because 685551 - 2² = 685547 is a prime.

It is a D-number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (685511) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 114256 + ... + 114261.

It is an arithmetic number, because the mean of its divisors is an integer number (228518).

2⁶⁸⁵⁵⁵¹ is an apocalyptic number.

685551 is a deficient number, since it is larger than the sum of its proper divisors (228521).

685551 is a wasteful number, since it uses less digits than its factorization.

685551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 228520.

The product of its digits is 6000, while the sum is 30.

The square root of 685551 is about 827.9800722240. The cubic root of 685551 is about 88.1752276417.

The spelling of 685551 in words is "six hundred eighty-five thousand, five hundred fifty-one".