681966 has 32 divisors (see below), whose sum is σ = 1545120. Its totient is φ = 222912.

The previous prime is 681949. The next prime is 681971. The reversal of 681966 is 669186.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 681966.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3856 + ... + 4028.

It is an arithmetic number, because the mean of its divisors is an integer number (48285).

2⁶⁸¹⁹⁶⁶ is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 681966, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (772560).

681966 is an abundant number, since it is smaller than the sum of its proper divisors (863154).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

681966 is a wasteful number, since it uses less digits than its factorization.

681966 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 257 (or 251 counting only the distinct ones).

The product of its digits is 15552, while the sum is 36.

The square root of 681966 is about 825.8123273480. The cubic root of 681966 is about 88.0212586381.

It can be divided in two parts, 6819 and 66, that multiplied together give a palindrome (450054).

The spelling of 681966 in words is "six hundred eighty-one thousand, nine hundred sixty-six".