681321698 has 6 divisors (see below), whose sum is σ = 1022037921. Its totient is φ = 340642392.

The previous prime is 681321691. The next prime is 681321821. The reversal of 681321698 is 896123186.

It can be written as a sum of positive squares in 2 ways, for example, as 639938209 + 41383489 = 25297^2 + 6433^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=18457.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (681321691) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 27686 + ... + 46142.

Almost surely, 2^681321698 is an apocalyptic number.

681321698 is a deficient number, since it is larger than the sum of its proper divisors (340716223).

681321698 is an frugal number, since it uses more digits than its factorization.

681321698 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36916 (or 18459 counting only the distinct ones).

The product of its digits is 124416, while the sum is 44.

The square root of 681321698 is about 26102.1397207202. The cubic root of 681321698 is about 879.9352991343.

The spelling of 681321698 in words is "six hundred eighty-one million, three hundred twenty-one thousand, six hundred ninety-eight".