663865 has 8 divisors (see below), whose sum is σ = 822528. Its totient is φ = 513840.

The previous prime is 663857. The next prime is 663869. The reversal of 663865 is 568366.

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

It is not a de Polignac number, because 663865 - 2³ = 663857 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 663865.

It is not an unprimeable number, because it can be changed into a prime (663869) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1987 + ... + 2296.

It is an arithmetic number, because the mean of its divisors is an integer number (102816).

2⁶⁶³⁸⁶⁵ is an apocalyptic number.

It is an amenable number.

663865 is a deficient number, since it is larger than the sum of its proper divisors (158663).

663865 is a wasteful number, since it uses less digits than its factorization.

663865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4319.

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

The square root of 663865 is about 814.7791111706. The cubic root of 663865 is about 87.2355005832.

The spelling of 663865 in words is "six hundred sixty-three thousand, eight hundred sixty-five".