685238100091 has 2 divisors, whose sum is σ = 685238100092. Its totient is φ = 685238100090.

The previous prime is 685238100049. The next prime is 685238100101. The reversal of 685238100091 is 190001832586.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 685238100091 - 2¹¹ = 685238098043 is a prime.

It is not a weakly prime, because it can be changed into another prime (685238100011) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 342619050045 + 342619050046.

It is an arithmetic number, because the mean of its divisors is an integer number (342619050046).

Almost surely, 2^685238100091 is an apocalyptic number.

685238100091 is a deficient number, since it is larger than the sum of its proper divisors (1).

685238100091 is an equidigital number, since it uses as much as digits as its factorization.

685238100091 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 103680, while the sum is 43.

The spelling of 685238100091 in words is "six hundred eighty-five billion, two hundred thirty-eight million, one hundred thousand, ninety-one".