681630217 has 2 divisors, whose sum is σ = 681630218. Its totient is φ = 681630216.

The previous prime is 681630203. The next prime is 681630221. The reversal of 681630217 is 712036186.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 571401216 + 110229001 = 23904^2 + 10499^2 .

It is a cyclic number.

It is not a de Polignac number, because 681630217 - 2²³ = 673241609 is a prime.

It is not a weakly prime, because it can be changed into another prime (681630227) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 340815108 + 340815109.

It is an arithmetic number, because the mean of its divisors is an integer number (340815109).

Almost surely, 2^681630217 is an apocalyptic number.

It is an amenable number.

681630217 is a deficient number, since it is larger than the sum of its proper divisors (1).

681630217 is an equidigital number, since it uses as much as digits as its factorization.

681630217 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 12096, while the sum is 34.

The square root of 681630217 is about 26108.0488930138. The cubic root of 681630217 is about 880.0680977777.

The spelling of 681630217 in words is "six hundred eighty-one million, six hundred thirty thousand, two hundred seventeen".