191681 has 8 divisors (see below), whose sum is σ = 221760. Its totient is φ = 162288.

The previous prime is 191677. The next prime is 191689. The reversal of 191681 is 186191.

191681 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is not a de Polignac number, because 191681 - 2² = 191677 is a prime.

It is a super-2 number, since 2×191681² = 73483211522, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 191681.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 191681.

It is not an unprimeable number, because it can be changed into a prime (191689) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 875 + ... + 1071.

It is an arithmetic number, because the mean of its divisors is an integer number (27720).

2¹⁹¹⁶⁸¹ is an apocalyptic number.

It is an amenable number.

191681 is a deficient number, since it is larger than the sum of its proper divisors (30079).

191681 is a wasteful number, since it uses less digits than its factorization.

191681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 343.

The product of its digits is 432, while the sum is 26.

The square root of 191681 is about 437.8138873997. The cubic root of 191681 is about 57.6580152673.

The spelling of 191681 in words is "one hundred ninety-one thousand, six hundred eighty-one".