681743849 has 2 divisors, whose sum is σ = 681743850. Its totient is φ = 681743848.

The previous prime is 681743791. The next prime is 681743873. The reversal of 681743849 is 948347186.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 599515225 + 82228624 = 24485^2 + 9068^2 .

It is a cyclic number.

It is not a de Polignac number, because 681743849 - 2⁸ = 681743593 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 681743797 and 681743806.

It is not a weakly prime, because it can be changed into another prime (681743899) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 340871924 + 340871925.

It is an arithmetic number, because the mean of its divisors is an integer number (340871925).

Almost surely, 2^681743849 is an apocalyptic number.

It is an amenable number.

681743849 is a deficient number, since it is larger than the sum of its proper divisors (1).

681743849 is an equidigital number, since it uses as much as digits as its factorization.

681743849 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1161216, while the sum is 50.

The square root of 681743849 is about 26110.2249894558. The cubic root of 681743849 is about 880.1169993371.

The spelling of 681743849 in words is "six hundred eighty-one million, seven hundred forty-three thousand, eight hundred forty-nine".