685078181 has 2 divisors, whose sum is σ = 685078182. Its totient is φ = 685078180.

The previous prime is 685078169. The next prime is 685078321. The reversal of 685078181 is 181870586.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 586075681 + 99002500 = 24209^2 + 9950^2 .

It is a cyclic number.

It is not a de Polignac number, because 685078181 - 2¹⁸ = 684816037 is a prime.

It is a super-2 number, since 2×685078181² = 938664228164537522, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (685078481) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 342539090 + 342539091.

It is an arithmetic number, because the mean of its divisors is an integer number (342539091).

Almost surely, 2^685078181 is an apocalyptic number.

It is an amenable number.

685078181 is a deficient number, since it is larger than the sum of its proper divisors (1).

685078181 is an equidigital number, since it uses as much as digits as its factorization.

685078181 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 107520, while the sum is 44.

The square root of 685078181 is about 26173.9981852219. The cubic root of 685078181 is about 881.5495173163.

The spelling of 685078181 in words is "six hundred eighty-five million, seventy-eight thousand, one hundred eighty-one".