685646617 has 2 divisors, whose sum is σ = 685646618. Its totient is φ = 685646616.

The previous prime is 685646581. The next prime is 685646657. The reversal of 685646617 is 716646586.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 525143056 + 160503561 = 22916^2 + 12669^2 .

It is a cyclic number.

It is not a de Polignac number, because 685646617 - 2¹⁹ = 685122329 is a prime.

It is a super-2 number, since 2×685646617² = 940222566807089378, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (685646657) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 342823308 + 342823309.

It is an arithmetic number, because the mean of its divisors is an integer number (342823309).

Almost surely, 2^685646617 is an apocalyptic number.

It is an amenable number.

685646617 is a deficient number, since it is larger than the sum of its proper divisors (1).

685646617 is an equidigital number, since it uses as much as digits as its factorization.

685646617 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1451520, while the sum is 49.

The square root of 685646617 is about 26184.8547255852. The cubic root of 685646617 is about 881.7932685474.

The spelling of 685646617 in words is "six hundred eighty-five million, six hundred forty-six thousand, six hundred seventeen".