686605049 has 4 divisors (see below), whose sum is σ = 739420836. Its totient is φ = 633789264.

The previous prime is 686605043. The next prime is 686605057. The reversal of 686605049 is 940506686.

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 434430649 + 252174400 = 20843^2 + 15880^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-686605049 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (686605043) 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, 26407874 + ... + 26407899.

It is an arithmetic number, because the mean of its divisors is an integer number (184855209).

Almost surely, 2^686605049 is an apocalyptic number.

It is an amenable number.

686605049 is a deficient number, since it is larger than the sum of its proper divisors (52815787).

686605049 is a wasteful number, since it uses less digits than its factorization.

686605049 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52815786.

The product of its (nonzero) digits is 311040, while the sum is 44.

The square root of 686605049 is about 26203.1496007636. The cubic root of 686605049 is about 882.2039491992.

The spelling of 686605049 in words is "six hundred eighty-six million, six hundred five thousand, forty-nine".