681666 has 32 divisors (see below), whose sum is σ = 1487808. Its totient is φ = 207360.

The previous prime is 681647. The next prime is 681673. The reversal of 681666 is 666186.

It is a Curzon number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 681666.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4101 + ... + 4263.

It is an arithmetic number, because the mean of its divisors is an integer number (46494).

2⁶⁸¹⁶⁶⁶ is an apocalyptic number.

681666 is an abundant number, since it is smaller than the sum of its proper divisors (806142).

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

681666 is a wasteful number, since it uses less digits than its factorization.

681666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 226.

The product of its digits is 10368, while the sum is 33.

The square root of 681666 is about 825.6306680350. The cubic root of 681666 is about 88.0083497587.

The spelling of 681666 in words is "six hundred eighty-one thousand, six hundred sixty-six".