16691 has 2 divisors, whose sum is σ = 16692. Its totient is φ = 16690.

The previous prime is 16673. The next prime is 16693. The reversal of 16691 is 19661.

It is a strong prime.

It is an emirp because it is prime and its reverse (19661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 16691 - 2¹⁰ = 15667 is a prime.

Together with 16693, it forms a pair of twin primes.

It is a Chen prime.

It is a plaindrome in base 13.

It is a nialpdrome in base 7.

It is not a weakly prime, because it can be changed into another prime (16693) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8345 + 8346.

It is an arithmetic number, because the mean of its divisors is an integer number (8346).

2¹⁶⁶⁹¹ is an apocalyptic number.

16691 is a deficient number, since it is larger than the sum of its proper divisors (1).

16691 is an equidigital number, since it uses as much as digits as its factorization.

16691 is an evil number, because the sum of its binary digits is even.

The product of its digits is 324, while the sum is 23.

The square root of 16691 is about 129.1936530949. The cubic root of 16691 is about 25.5560729434.

It can be divided in two parts, 16 and 691, that added together give a palindrome (707).

The spelling of 16691 in words is "sixteen thousand, six hundred ninety-one".