681291857 has 2 divisors, whose sum is σ = 681291858. Its totient is φ = 681291856.

The previous prime is 681291833. The next prime is 681291869. The reversal of 681291857 is 758192186.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 680218561 + 1073296 = 26081^2 + 1036^2 .

It is a cyclic number.

It is not a de Polignac number, because 681291857 - 2¹⁰ = 681290833 is a prime.

It is not a weakly prime, because it can be changed into another prime (681291757) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 340645928 + 340645929.

It is an arithmetic number, because the mean of its divisors is an integer number (340645929).

Almost surely, 2^681291857 is an apocalyptic number.

It is an amenable number.

681291857 is a deficient number, since it is larger than the sum of its proper divisors (1).

681291857 is an equidigital number, since it uses as much as digits as its factorization.

681291857 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 241920, while the sum is 47.

The square root of 681291857 is about 26101.5680946567. The cubic root of 681291857 is about 879.9224522746.

The spelling of 681291857 in words is "six hundred eighty-one million, two hundred ninety-one thousand, eight hundred fifty-seven".