681336857 has 2 divisors, whose sum is σ = 681336858. Its totient is φ = 681336856.

The previous prime is 681336841. The next prime is 681336881. The reversal of 681336857 is 758633186.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 433305856 + 248031001 = 20816^2 + 15749^2 .

It is a cyclic number.

It is not a de Polignac number, because 681336857 - 2⁴ = 681336841 is a prime.

It is not a weakly prime, because it can be changed into another prime (681332857) 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, 340668428 + 340668429.

It is an arithmetic number, because the mean of its divisors is an integer number (340668429).

Almost surely, 2^681336857 is an apocalyptic number.

It is an amenable number.

681336857 is a deficient number, since it is larger than the sum of its proper divisors (1).

681336857 is an equidigital number, since it uses as much as digits as its factorization.

681336857 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 725760, while the sum is 47.

The square root of 681336857 is about 26102.4300975982. The cubic root of 681336857 is about 879.9418250971.

The spelling of 681336857 in words is "six hundred eighty-one million, three hundred thirty-six thousand, eight hundred fifty-seven".