15691 has 8 divisors (see below), whose sum is σ = 18144.
Its totient is φ = 13440.
The previous prime is 15683. The next prime is 15727. The reversal of 15691 is 19651.
It is a sphenic number, since it is the product of 3 distinct primes.
It is a cyclic number.
It is not a de Polignac number, because 15691 - 23 = 15683 is a prime.
It is a Duffinian number.
It is not an unprimeable number, because it can be changed into a prime (15601) 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, 186 + ... + 256.
It is an arithmetic number, because the mean of its divisors is an integer number (2268).
215691 is an apocalyptic number.
15691 is a deficient number, since it is larger than the sum of its proper divisors (2453).
15691 is a wasteful number, since it uses less digits than its factorization.
15691 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 101.
The product of its digits is 270, while the sum is 22.
The square root of 15691 is about 125.2637218032.
The cubic root of 15691 is about 25.0351505544.
It can be divided in two parts, 156 and 91, that multiplied together give a triangular number (14196 = T168).
The spelling of 15691 in words is "fifteen thousand, six hundred ninety-one".