681681 has 32 divisors (see below), whose sum is σ = 1225728. Its totient is φ = 325440.

The previous prime is 681677. The next prime is 681689. The reversal of 681681 is 186186.

681681 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 681681 - 2² = 681677 is a prime.

It is a super-2 number, since 2×681681² = 929377971522, which contains 22 as substring.

It is a zygodrome in base 6.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 681681.

It is not an unprimeable number, because it can be changed into a prime (681689) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2890 + ... + 3116.

It is an arithmetic number, because the mean of its divisors is an integer number (38304).

2⁶⁸¹⁶⁸¹ is an apocalyptic number.

It is an amenable number.

681681 is a deficient number, since it is larger than the sum of its proper divisors (544047).

681681 is a wasteful number, since it uses less digits than its factorization.

681681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 261.

The product of its digits is 2304, while the sum is 30.

The square root of 681681 is about 825.6397519500. The cubic root of 681681 is about 88.0089952926.

The spelling of 681681 in words is "six hundred eighty-one thousand, six hundred eighty-one".