685861871 has 2 divisors, whose sum is σ = 685861872. Its totient is φ = 685861870.

The previous prime is 685861831. The next prime is 685861873. The reversal of 685861871 is 178168586.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 685861871 - 2⁶ = 685861807 is a prime.

Together with 685861873, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (685861873) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 342930935 + 342930936.

It is an arithmetic number, because the mean of its divisors is an integer number (342930936).

Almost surely, 2^685861871 is an apocalyptic number.

685861871 is a deficient number, since it is larger than the sum of its proper divisors (1).

685861871 is an equidigital number, since it uses as much as digits as its factorization.

685861871 is an evil number, because the sum of its binary digits is even.

The product of its digits is 645120, while the sum is 50.

The square root of 685861871 is about 26188.9646798036. The cubic root of 685861871 is about 881.8855365194.

The spelling of 685861871 in words is "six hundred eighty-five million, eight hundred sixty-one thousand, eight hundred seventy-one".