15866 has 4 divisors (see below), whose sum is σ = 23802. Its totient is φ = 7932.

The previous prime is 15859. The next prime is 15877. The reversal of 15866 is 66851.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 14641 + 1225 = 121^2 + 35^2 .

It is a plaindrome in base 9.

It is a nialpdrome in base 12.

It is an unprimeable number.

15866 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3965 + ... + 3968.

2¹⁵⁸⁶⁶ is an apocalyptic number.

15866 is a deficient number, since it is larger than the sum of its proper divisors (7936).

15866 is an equidigital number, since it uses as much as digits as its factorization.

15866 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7935.

The product of its digits is 1440, while the sum is 26.

The square root of 15866 is about 125.9603112095. The cubic root of 15866 is about 25.1278781056.

The spelling of 15866 in words is "fifteen thousand, eight hundred sixty-six".