685777 has 4 divisors (see below), whose sum is σ = 700416. Its totient is φ = 671140.

The previous prime is 685759. The next prime is 685781. The reversal of 685777 is 777586.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 777586 = 2 ⋅388793.

It is a cyclic number.

It is not a de Polignac number, because 685777 - 2⁷ = 685649 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (685717) 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, 7249 + ... + 7342.

It is an arithmetic number, because the mean of its divisors is an integer number (175104).

2⁶⁸⁵⁷⁷⁷ is an apocalyptic number.

It is an amenable number.

685777 is a deficient number, since it is larger than the sum of its proper divisors (14639).

685777 is a wasteful number, since it uses less digits than its factorization.

685777 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14638.

The product of its digits is 82320, while the sum is 40.

The square root of 685777 is about 828.1165376926. The cubic root of 685777 is about 88.1849159129.

Subtracting 685777 from its reverse (777586), we obtain a square (91809 = 303²).

The spelling of 685777 in words is "six hundred eighty-five thousand, seven hundred seventy-seven".