685639061 has 2 divisors, whose sum is σ = 685639062. Its totient is φ = 685639060.

The previous prime is 685639057. The next prime is 685639063. The reversal of 685639061 is 160936586.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 567916561 + 117722500 = 23831^2 + 10850^2 .

It is a cyclic number.

It is not a de Polignac number, because 685639061 - 2² = 685639057 is a prime.

Together with 685639063, 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 (685639063) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 342819530 + 342819531.

It is an arithmetic number, because the mean of its divisors is an integer number (342819531).

Almost surely, 2^685639061 is an apocalyptic number.

It is an amenable number.

685639061 is a deficient number, since it is larger than the sum of its proper divisors (1).

685639061 is an equidigital number, since it uses as much as digits as its factorization.

685639061 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 233280, while the sum is 44.

The square root of 685639061 is about 26184.7104433102. The cubic root of 685639061 is about 881.7900293402.

The spelling of 685639061 in words is "six hundred eighty-five million, six hundred thirty-nine thousand, sixty-one".