681671 has 4 divisors (see below), whose sum is σ = 691344. Its totient is φ = 672000.

The previous prime is 681647. The next prime is 681673. The reversal of 681671 is 176186.

681671 = T₁₈ + T₁₉ + ... + T₁₅₉.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 176186 = 2 ⋅88093.

It is a cyclic number.

It is not a de Polignac number, because 681671 - 2⁶ = 681607 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (681673) 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 in 3 ways as a sum of consecutive naturals, for example, 4730 + ... + 4871.

It is an arithmetic number, because the mean of its divisors is an integer number (172836).

2⁶⁸¹⁶⁷¹ is an apocalyptic number.

681671 is a deficient number, since it is larger than the sum of its proper divisors (9673).

681671 is an equidigital number, since it uses as much as digits as its factorization.

681671 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9672.

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

The square root of 681671 is about 825.6336960178. The cubic root of 681671 is about 88.0085649377.

The spelling of 681671 in words is "six hundred eighty-one thousand, six hundred seventy-one".