815866 has 8 divisors (see below), whose sum is σ = 1227744. Its totient is φ = 406620.

The previous prime is 815851. The next prime is 815869. The reversal of 815866 is 668518.

It is a happy number.

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

It is not an unprimeable number, because it can be changed into a prime (815869) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 601 + ... + 1411.

It is an arithmetic number, because the mean of its divisors is an integer number (153468).

2⁸¹⁵⁸⁶⁶ is an apocalyptic number.

815866 is a deficient number, since it is larger than the sum of its proper divisors (411878).

815866 is a wasteful number, since it uses less digits than its factorization.

815866 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1316.

The product of its digits is 11520, while the sum is 34.

The square root of 815866 is about 903.2530099590. The cubic root of 815866 is about 93.4414591560.

It can be divided in two parts, 815 and 866, that added together give a square (1681 = 41²).

The spelling of 815866 in words is "eight hundred fifteen thousand, eight hundred sixty-six".