681844 has 12 divisors (see below), whose sum is σ = 1199044. Its totient is φ = 339264.

The previous prime is 681841. The next prime is 681883. The reversal of 681844 is 448186.

It can be written as a sum of positive squares in 2 ways, for example, as 490000 + 191844 = 700^2 + 438^2 .

It is a super-2 number, since 2×681844² = 929822480672, which contains 22 as substring.

It is a hoax number, since the sum of its digits (31) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (681841) 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, 1264 + ... + 1720.

2⁶⁸¹⁸⁴⁴ is an apocalyptic number.

It is an amenable number.

681844 is a deficient number, since it is larger than the sum of its proper divisors (517200).

681844 is a wasteful number, since it uses less digits than its factorization.

681844 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 834 (or 832 counting only the distinct ones).

The product of its digits is 6144, while the sum is 31.

The square root of 681844 is about 825.7384573822. The cubic root of 681844 is about 88.0160094840.

It can be divided in two parts, 6818 and 44, that multiplied together give a palindrome (299992).

The spelling of 681844 in words is "six hundred eighty-one thousand, eight hundred forty-four".