816815 has 4 divisors (see below), whose sum is σ = 980184. Its totient is φ = 653448.

The previous prime is 816811. The next prime is 816817. The reversal of 816815 is 518618.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 518618 = 2 ⋅259309.

It is a cyclic number.

It is not a de Polignac number, because 816815 - 2² = 816811 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (816811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 81677 + ... + 81686.

It is an arithmetic number, because the mean of its divisors is an integer number (245046).

2⁸¹⁶⁸¹⁵ is an apocalyptic number.

816815 is a deficient number, since it is larger than the sum of its proper divisors (163369).

816815 is a wasteful number, since it uses less digits than its factorization.

816815 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 163368.

The product of its digits is 1920, while the sum is 29.

The square root of 816815 is about 903.7781807501. The cubic root of 816815 is about 93.4776749009.

The spelling of 816815 in words is "eight hundred sixteen thousand, eight hundred fifteen".