685909649 has 2 divisors, whose sum is σ = 685909650. Its totient is φ = 685909648.

The previous prime is 685909643. The next prime is 685909667. The reversal of 685909649 is 946909586.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 550606225 + 135303424 = 23465^2 + 11632^2 .

It is a cyclic number.

It is not a de Polignac number, because 685909649 - 2¹² = 685905553 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 685909594 and 685909603.

It is not a weakly prime, because it can be changed into another prime (685909643) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 342954824 + 342954825.

It is an arithmetic number, because the mean of its divisors is an integer number (342954825).

Almost surely, 2^685909649 is an apocalyptic number.

It is an amenable number.

685909649 is a deficient number, since it is larger than the sum of its proper divisors (1).

685909649 is an equidigital number, since it uses as much as digits as its factorization.

685909649 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4199040, while the sum is 56.

The square root of 685909649 is about 26189.8768420166. The cubic root of 685909649 is about 881.9060137955.

The spelling of 685909649 in words is "six hundred eighty-five million, nine hundred nine thousand, six hundred forty-nine".