671681 has 2 divisors, whose sum is σ = 671682. Its totient is φ = 671680.

The previous prime is 671651. The next prime is 671701. The reversal of 671681 is 186176.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 341056 + 330625 = 584^2 + 575^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-671681 is a prime.

It is a super-2 number, since 2×671681² = 902310731522, which contains 22 as substring.

It is a Chen prime.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 671681.

It is not a weakly prime, because it can be changed into another prime (671651) 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, 335840 + 335841.

It is an arithmetic number, because the mean of its divisors is an integer number (335841).

2⁶⁷¹⁶⁸¹ is an apocalyptic number.

It is an amenable number.

671681 is a deficient number, since it is larger than the sum of its proper divisors (1).

671681 is an equidigital number, since it uses as much as digits as its factorization.

671681 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2016, while the sum is 29.

The square root of 671681 is about 819.5614681035. The cubic root of 671681 is about 87.5765208163.

The spelling of 671681 in words is "six hundred seventy-one thousand, six hundred eighty-one".