665816 has 8 divisors (see below), whose sum is σ = 1248420. Its totient is φ = 332904.

The previous prime is 665813. The next prime is 665843. The reversal of 665816 is 618566.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 665816.

It is not an unprimeable number, because it can be changed into a prime (665813) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 41606 + ... + 41621.

2⁶⁶⁵⁸¹⁶ is an apocalyptic number.

It is an amenable number.

665816 is a deficient number, since it is larger than the sum of its proper divisors (582604).

665816 is a wasteful number, since it uses less digits than its factorization.

665816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 83233 (or 83229 counting only the distinct ones).

The product of its digits is 8640, while the sum is 32.

The square root of 665816 is about 815.9754898280. The cubic root of 665816 is about 87.3208743695.

The spelling of 665816 in words is "six hundred sixty-five thousand, eight hundred sixteen".