686820691 has 2 divisors, whose sum is σ = 686820692. Its totient is φ = 686820690.

The previous prime is 686820679. The next prime is 686820709. The reversal of 686820691 is 196028686.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-686820691 is a prime.

It is not a weakly prime, because it can be changed into another prime (686820611) 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 as a sum of consecutive naturals, namely, 343410345 + 343410346.

It is an arithmetic number, because the mean of its divisors is an integer number (343410346).

Almost surely, 2^686820691 is an apocalyptic number.

686820691 is a deficient number, since it is larger than the sum of its proper divisors (1).

686820691 is an equidigital number, since it uses as much as digits as its factorization.

686820691 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 248832, while the sum is 46.

The square root of 686820691 is about 26207.2640884164. The cubic root of 686820691 is about 882.2962974429.

The spelling of 686820691 in words is "six hundred eighty-six million, eight hundred twenty thousand, six hundred ninety-one".