681840529 has 2 divisors, whose sum is σ = 681840530. Its totient is φ = 681840528.

The previous prime is 681840503. The next prime is 681840557. The reversal of 681840529 is 925048186.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 674960400 + 6880129 = 25980^2 + 2623^2 .

It is a cyclic number.

It is not a de Polignac number, because 681840529 - 2¹⁹ = 681316241 is a prime.

It is not a weakly prime, because it can be changed into another prime (681840829) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 340920264 + 340920265.

It is an arithmetic number, because the mean of its divisors is an integer number (340920265).

Almost surely, 2^681840529 is an apocalyptic number.

It is an amenable number.

681840529 is a deficient number, since it is larger than the sum of its proper divisors (1).

681840529 is an equidigital number, since it uses as much as digits as its factorization.

681840529 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 138240, while the sum is 43.

The square root of 681840529 is about 26112.0763058015. The cubic root of 681840529 is about 880.1586013208.

The spelling of 681840529 in words is "six hundred eighty-one million, eight hundred forty thousand, five hundred twenty-nine".