685778391539 has 2 divisors, whose sum is σ = 685778391540. Its totient is φ = 685778391538.

The previous prime is 685778391517. The next prime is 685778391589. The reversal of 685778391539 is 935193877586.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 685778391539 - 2¹⁶ = 685778326003 is a prime.

It is not a weakly prime, because it can be changed into another prime (685778391509) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 342889195769 + 342889195770.

It is an arithmetic number, because the mean of its divisors is an integer number (342889195770).

Almost surely, 2^685778391539 is an apocalyptic number.

685778391539 is a deficient number, since it is larger than the sum of its proper divisors (1).

685778391539 is an equidigital number, since it uses as much as digits as its factorization.

685778391539 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 342921600, while the sum is 71.

The spelling of 685778391539 in words is "six hundred eighty-five billion, seven hundred seventy-eight million, three hundred ninety-one thousand, five hundred thirty-nine".