865663 has 4 divisors (see below), whose sum is σ = 867888. Its totient is φ = 863440.

The previous prime is 865661. The next prime is 865681. The reversal of 865663 is 366568.

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

It is a cyclic number.

It is not a de Polignac number, because 865663 - 2¹ = 865661 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 (865661) 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, 358 + ... + 1363.

It is an arithmetic number, because the mean of its divisors is an integer number (216972).

2⁸⁶⁵⁶⁶³ is an apocalyptic number.

865663 is a deficient number, since it is larger than the sum of its proper divisors (2225).

865663 is a wasteful number, since it uses less digits than its factorization.

865663 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2224.

The product of its digits is 25920, while the sum is 34.

The square root of 865663 is about 930.4101246225. The cubic root of 865663 is about 95.3051315454.

The spelling of 865663 in words is "eight hundred sixty-five thousand, six hundred sixty-three".