691986 has 8 divisors (see below), whose sum is σ = 1383984. Its totient is φ = 230660.

The previous prime is 691979. The next prime is 691991. The reversal of 691986 is 689196.

It is a sphenic number, since it is the product of 3 distinct primes.

691986 is an admirable number.

It is an unprimeable number.

691986 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 57660 + ... + 57671.

It is an arithmetic number, because the mean of its divisors is an integer number (172998).

2⁶⁹¹⁹⁸⁶ is an apocalyptic number.

691986 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

691986 is a wasteful number, since it uses less digits than its factorization.

691986 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 115336.

The product of its digits is 23328, while the sum is 39.

The square root of 691986 is about 831.8569588577. The cubic root of 691986 is about 88.4502577249.

The spelling of 691986 in words is "six hundred ninety-one thousand, nine hundred eighty-six".