15666 has 16 divisors (see below), whose sum is σ = 35904. Its totient is φ = 4464.

The previous prime is 15661. The next prime is 15667. The reversal of 15666 is 66651.

It is a Curzon number.

It is a plaindrome in base 10.

It is not an unprimeable number, because it can be changed into a prime (15661) 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, 145 + ... + 228.

It is an arithmetic number, because the mean of its divisors is an integer number (2244).

2¹⁵⁶⁶⁶ is an apocalyptic number.

15666 is an abundant number, since it is smaller than the sum of its proper divisors (20238).

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

It is a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (17952).

15666 is a wasteful number, since it uses less digits than its factorization.

15666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 385.

The product of its digits is 1080, while the sum is 24.

The square root of 15666 is about 125.1638925569. The cubic root of 15666 is about 25.0218475685.

It can be divided in two parts, 156 and 66, that multiplied together give a triangular number (10296 = T₁₄₃).

The spelling of 15666 in words is "fifteen thousand, six hundred sixty-six".