681214561 has 2 divisors, whose sum is σ = 681214562. Its totient is φ = 681214560.

The previous prime is 681214559. The next prime is 681214571. The reversal of 681214561 is 165412186.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 568536336 + 112678225 = 23844^2 + 10615^2 .

It is a cyclic number.

It is not a de Polignac number, because 681214561 - 2¹ = 681214559 is a prime.

Together with 681214559, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (681214571) 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, 340607280 + 340607281.

It is an arithmetic number, because the mean of its divisors is an integer number (340607281).

Almost surely, 2^681214561 is an apocalyptic number.

It is an amenable number.

681214561 is a deficient number, since it is larger than the sum of its proper divisors (1).

681214561 is an equidigital number, since it uses as much as digits as its factorization.

681214561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 11520, while the sum is 34.

The square root of 681214561 is about 26100.0873753327. The cubic root of 681214561 is about 879.8891738015.

The spelling of 681214561 in words is "six hundred eighty-one million, two hundred fourteen thousand, five hundred sixty-one".