815965 has 4 divisors (see below), whose sum is σ = 979164. Its totient is φ = 652768.

The previous prime is 815963. The next prime is 815977. The reversal of 815965 is 569518.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 569518 = 2 ⋅284759.

It can be written as a sum of positive squares in 2 ways, for example, as 605284 + 210681 = 778^2 + 459^2 .

It is a cyclic number.

It is not a de Polignac number, because 815965 - 2¹ = 815963 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 815965.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (815963) 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, 81592 + ... + 81601.

It is an arithmetic number, because the mean of its divisors is an integer number (244791).

2⁸¹⁵⁹⁶⁵ is an apocalyptic number.

It is an amenable number.

815965 is a deficient number, since it is larger than the sum of its proper divisors (163199).

815965 is a wasteful number, since it uses less digits than its factorization.

815965 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 163198.

The product of its digits is 10800, while the sum is 34.

The square root of 815965 is about 903.3078102175. The cubic root of 815965 is about 93.4452385063.

The spelling of 815965 in words is "eight hundred fifteen thousand, nine hundred sixty-five".