681971 has 2 divisors, whose sum is σ = 681972. Its totient is φ = 681970.

The previous prime is 681949. The next prime is 681977. The reversal of 681971 is 179186.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 681971 - 2¹⁸ = 419827 is a prime.

It is not a weakly prime, because it can be changed into another prime (681977) 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, 340985 + 340986.

It is an arithmetic number, because the mean of its divisors is an integer number (340986).

2⁶⁸¹⁹⁷¹ is an apocalyptic number.

681971 is a deficient number, since it is larger than the sum of its proper divisors (1).

681971 is an equidigital number, since it uses as much as digits as its factorization.

681971 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3024, while the sum is 32.

The square root of 681971 is about 825.8153546647. The cubic root of 681971 is about 88.0214737540.

The spelling of 681971 in words is "six hundred eighty-one thousand, nine hundred seventy-one".