686321691 has 16 divisors (see below), whose sum is σ = 1011964800. Its totient is φ = 410253120.

The previous prime is 686321687. The next prime is 686321693. The reversal of 686321691 is 196123686.

It is not a de Polignac number, because 686321691 - 2² = 686321687 is a prime.

It is not an unprimeable number, because it can be changed into a prime (686321693) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 140041 + ... + 144858.

It is an arithmetic number, because the mean of its divisors is an integer number (63247800).

Almost surely, 2^686321691 is an apocalyptic number.

686321691 is a deficient number, since it is larger than the sum of its proper divisors (325643109).

686321691 is a wasteful number, since it uses less digits than its factorization.

686321691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 284986.

The product of its digits is 93312, while the sum is 42.

The square root of 686321691 is about 26197.7420973640. The cubic root of 686321691 is about 882.0825723158.

The spelling of 686321691 in words is "six hundred eighty-six million, three hundred twenty-one thousand, six hundred ninety-one".