681397861 has 4 divisors (see below), whose sum is σ = 682122924. Its totient is φ = 680672800.

The previous prime is 681397853. The next prime is 681397867. The reversal of 681397861 is 168793186.

681397861 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 509630625 + 171767236 = 22575^2 + 13106^2 .

It is a cyclic number.

It is not a de Polignac number, because 681397861 - 2³ = 681397853 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (681397867) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 361120 + ... + 363001.

It is an arithmetic number, because the mean of its divisors is an integer number (170530731).

Almost surely, 2^681397861 is an apocalyptic number.

It is an amenable number.

681397861 is a deficient number, since it is larger than the sum of its proper divisors (725063).

681397861 is an equidigital number, since it uses as much as digits as its factorization.

681397861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 725062.

The product of its digits is 435456, while the sum is 49.

The square root of 681397861 is about 26103.5986216460. The cubic root of 681397861 is about 879.9680863943.

The spelling of 681397861 in words is "six hundred eighty-one million, three hundred ninety-seven thousand, eight hundred sixty-one".