681745249 has 2 divisors, whose sum is σ = 681745250. Its totient is φ = 681745248.

The previous prime is 681745223. The next prime is 681745279. The reversal of 681745249 is 942547186.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 440160400 + 241584849 = 20980^2 + 15543^2 .

It is a cyclic number.

It is not a de Polignac number, because 681745249 - 2²³ = 673356641 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 681745199 and 681745208.

It is not a weakly prime, because it can be changed into another prime (681745279) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 340872624 + 340872625.

It is an arithmetic number, because the mean of its divisors is an integer number (340872625).

Almost surely, 2^681745249 is an apocalyptic number.

It is an amenable number.

681745249 is a deficient number, since it is larger than the sum of its proper divisors (1).

681745249 is an equidigital number, since it uses as much as digits as its factorization.

681745249 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 483840, while the sum is 46.

The square root of 681745249 is about 26110.2517988625. The cubic root of 681745249 is about 880.1176017935.

The spelling of 681745249 in words is "six hundred eighty-one million, seven hundred forty-five thousand, two hundred forty-nine".