685915519609 has 2 divisors, whose sum is σ = 685915519610. Its totient is φ = 685915519608.

The previous prime is 685915519519. The next prime is 685915519651. The reversal of 685915519609 is 906915519586.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 514416003984 + 171499515625 = 717228^2 + 414125^2 .

It is a cyclic number.

It is not a de Polignac number, because 685915519609 - 2¹³ = 685915511417 is a prime.

It is not a weakly prime, because it can be changed into another prime (685915549609) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 342957759804 + 342957759805.

It is an arithmetic number, because the mean of its divisors is an integer number (342957759805).

Almost surely, 2^685915519609 is an apocalyptic number.

It is an amenable number.

685915519609 is a deficient number, since it is larger than the sum of its proper divisors (1).

685915519609 is an equidigital number, since it uses as much as digits as its factorization.

685915519609 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 26244000, while the sum is 64.

The spelling of 685915519609 in words is "six hundred eighty-five billion, nine hundred fifteen million, five hundred nineteen thousand, six hundred nine".