681806 has 4 divisors (see below), whose sum is σ = 1022712. Its totient is φ = 340902.

The previous prime is 681787. The next prime is 681809. The reversal of 681806 is 608186.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 681806.

It is not an unprimeable number, because it can be changed into a prime (681809) by changing a digit.

681806 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

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, 170450 + ... + 170453.

It is an arithmetic number, because the mean of its divisors is an integer number (255678).

2⁶⁸¹⁸⁰⁶ is an apocalyptic number.

681806 is a deficient number, since it is larger than the sum of its proper divisors (340906).

681806 is a wasteful number, since it uses less digits than its factorization.

681806 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 340905.

The product of its (nonzero) digits is 2304, while the sum is 29.

The square root of 681806 is about 825.7154473546. The cubic root of 681806 is about 88.0143743737.

It can be divided in two parts, 68180 and 6, that added together give a palindrome (68186).

The spelling of 681806 in words is "six hundred eighty-one thousand, eight hundred six".