681997 has 2 divisors, whose sum is σ = 681998. Its totient is φ = 681996.

The previous prime is 681983. The next prime is 682001. The reversal of 681997 is 799186.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 670761 + 11236 = 819^2 + 106^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-681997 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (681977) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 340998 + 340999.

It is an arithmetic number, because the mean of its divisors is an integer number (340999).

2⁶⁸¹⁹⁹⁷ is an apocalyptic number.

It is an amenable number.

681997 is a deficient number, since it is larger than the sum of its proper divisors (1).

681997 is an equidigital number, since it uses as much as digits as its factorization.

681997 is an evil number, because the sum of its binary digits is even.

The product of its digits is 27216, while the sum is 40.

The square root of 681997 is about 825.8310965325. The cubic root of 681997 is about 88.0225923398.

The spelling of 681997 in words is "six hundred eighty-one thousand, nine hundred ninety-seven".