685738665 has 24 divisors (see below), whose sum is σ = 1192693320. Its totient is φ = 364472064.

The previous prime is 685738663. The next prime is 685738717. The reversal of 685738665 is 566837586.

685738665 is a `hidden beast` number, since 6 + 8 + 573 + 8 + 6 + 65 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 465394329 + 220344336 = 21573^2 + 14844^2 .

It is not a de Polignac number, because 685738665 - 2¹ = 685738663 is a prime.

It is not an unprimeable number, because it can be changed into a prime (685738663) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 12820 + ... + 39189.

It is an arithmetic number, because the mean of its divisors is an integer number (49695555).

Almost surely, 2^685738665 is an apocalyptic number.

It is an amenable number.

685738665 is a deficient number, since it is larger than the sum of its proper divisors (506954655).

685738665 is a wasteful number, since it uses less digits than its factorization.

685738665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52313 (or 52310 counting only the distinct ones).

The product of its digits is 7257600, while the sum is 54.

The square root of 685738665 is about 26186.6123238574. The cubic root of 685738665 is about 881.8327270054.

The spelling of 685738665 in words is "six hundred eighty-five million, seven hundred thirty-eight thousand, six hundred sixty-five".