815805 has 16 divisors (see below), whose sum is σ = 1450560. Its totient is φ = 435024.

The previous prime is 815729. The next prime is 815809. The reversal of 815805 is 508518.

815805 is a `hidden beast` number, since 81 + 580 + 5 = 666.

It is not a de Polignac number, because 815805 - 2¹² = 811709 is a prime.

It is a Smith number, since the sum of its digits (27) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (815809) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2887 + ... + 3156.

It is an arithmetic number, because the mean of its divisors is an integer number (90660).

2⁸¹⁵⁸⁰⁵ is an apocalyptic number.

It is an amenable number.

815805 is a deficient number, since it is larger than the sum of its proper divisors (634755).

815805 is a wasteful number, since it uses less digits than its factorization.

815805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6057 (or 6051 counting only the distinct ones).

The product of its (nonzero) digits is 1600, while the sum is 27.

The square root of 815805 is about 903.2192424877. The cubic root of 815805 is about 93.4391303131.

It can be divided in two parts, 81 and 5805, that added together give a triangular number (5886 = T₁₀₈).

The spelling of 815805 in words is "eight hundred fifteen thousand, eight hundred five".