686681291 has 4 divisors (see below), whose sum is σ = 687402792. Its totient is φ = 685959792.

The previous prime is 686681287. The next prime is 686681311. The reversal of 686681291 is 192186686.

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

It is a cyclic number.

It is not a de Polignac number, because 686681291 - 2² = 686681287 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (686681231) 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, 359321 + ... + 361226.

It is an arithmetic number, because the mean of its divisors is an integer number (171850698).

Almost surely, 2^686681291 is an apocalyptic number.

686681291 is a deficient number, since it is larger than the sum of its proper divisors (721501).

686681291 is an equidigital number, since it uses as much as digits as its factorization.

686681291 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 721500.

The product of its digits is 248832, while the sum is 47.

The square root of 686681291 is about 26204.6043854892. The cubic root of 686681291 is about 882.2366018885.

The spelling of 686681291 in words is "six hundred eighty-six million, six hundred eighty-one thousand, two hundred ninety-one".