686777909 has 2 divisors, whose sum is σ = 686777910. Its totient is φ = 686777908.

The previous prime is 686777899. The next prime is 686777929. The reversal of 686777909 is 909777686.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 495730225 + 191047684 = 22265^2 + 13822^2 .

It is a cyclic number.

It is not a de Polignac number, because 686777909 - 2²⁰ = 685729333 is a prime.

It is a super-3 number, since 3×686777909³ (a number of 27 digits) contains 333 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (686777929) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 343388954 + 343388955.

It is an arithmetic number, because the mean of its divisors is an integer number (343388955).

Almost surely, 2^686777909 is an apocalyptic number.

It is an amenable number.

686777909 is a deficient number, since it is larger than the sum of its proper divisors (1).

686777909 is an equidigital number, since it uses as much as digits as its factorization.

686777909 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8001504, while the sum is 59.

The square root of 686777909 is about 26206.4478516261. The cubic root of 686777909 is about 882.2779776764.

The spelling of 686777909 in words is "six hundred eighty-six million, seven hundred seventy-seven thousand, nine hundred nine".