686665279 has 2 divisors, whose sum is σ = 686665280. Its totient is φ = 686665278.

The previous prime is 686665261. The next prime is 686665303. The reversal of 686665279 is 972566686.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 686665279 - 2¹³ = 686657087 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (686665079) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 343332639 + 343332640.

It is an arithmetic number, because the mean of its divisors is an integer number (343332640).

Almost surely, 2^686665279 is an apocalyptic number.

686665279 is a deficient number, since it is larger than the sum of its proper divisors (1).

686665279 is an equidigital number, since it uses as much as digits as its factorization.

686665279 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6531840, while the sum is 55.

The square root of 686665279 is about 26204.2988648809. The cubic root of 686665279 is about 882.2297445189.

The spelling of 686665279 in words is "six hundred eighty-six million, six hundred sixty-five thousand, two hundred seventy-nine".