681722218057 has 2 divisors, whose sum is σ = 681722218058. Its totient is φ = 681722218056.

The previous prime is 681722217971. The next prime is 681722218061. The reversal of 681722218057 is 750812227186.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 561216732736 + 120505485321 = 749144^2 + 347139^2 .

It is a cyclic number.

It is not a de Polignac number, because 681722218057 - 2³⁵ = 647362479689 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 681722218057.

It is not a weakly prime, because it can be changed into another prime (681722216057) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 340861109028 + 340861109029.

It is an arithmetic number, because the mean of its divisors is an integer number (340861109029).

Almost surely, 2^681722218057 is an apocalyptic number.

It is an amenable number.

681722218057 is a deficient number, since it is larger than the sum of its proper divisors (1).

681722218057 is an equidigital number, since it uses as much as digits as its factorization.

681722218057 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 752640, while the sum is 49.

The spelling of 681722218057 in words is "six hundred eighty-one billion, seven hundred twenty-two million, two hundred eighteen thousand, fifty-seven".