131691 has 8 divisors (see below), whose sum is σ = 200704. Its totient is φ = 75240.

The previous prime is 131687. The next prime is 131701. The reversal of 131691 is 196131.

It is a happy number.

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

It is not a de Polignac number, because 131691 - 2² = 131687 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21), and also a Moran number because the ratio is a prime number: 6271 = 131691 / (1 + 3 + 1 + 6 + 9 + 1).

It is not an unprimeable number, because it can be changed into a prime (131611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3115 + ... + 3156.

It is an arithmetic number, because the mean of its divisors is an integer number (25088).

2¹³¹⁶⁹¹ is an apocalyptic number.

131691 is a deficient number, since it is larger than the sum of its proper divisors (69013).

131691 is an equidigital number, since it uses as much as digits as its factorization.

131691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6281.

The product of its digits is 162, while the sum is 21.

The square root of 131691 is about 362.8925460794. The cubic root of 131691 is about 50.8766724071.

The spelling of 131691 in words is "one hundred thirty-one thousand, six hundred ninety-one".