686015665 has 4 divisors (see below), whose sum is σ = 823218804. Its totient is φ = 548812528.

The previous prime is 686015651. The next prime is 686015669. The reversal of 686015665 is 566510686.

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

It can be written as a sum of positive squares in 2 ways, for example, as 381303729 + 304711936 = 19527^2 + 17456^2 .

It is a cyclic number.

It is not a de Polignac number, because 686015665 - 2⁷ = 686015537 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (686015669) 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, 68601562 + ... + 68601571.

It is an arithmetic number, because the mean of its divisors is an integer number (205804701).

Almost surely, 2^686015665 is an apocalyptic number.

It is an amenable number.

686015665 is a deficient number, since it is larger than the sum of its proper divisors (137203139).

686015665 is a wasteful number, since it uses less digits than its factorization.

686015665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 137203138.

The product of its (nonzero) digits is 259200, while the sum is 43.

The square root of 686015665 is about 26191.9007519500. The cubic root of 686015665 is about 881.9514480261.

The spelling of 686015665 in words is "six hundred eighty-six million, fifteen thousand, six hundred sixty-five".