665807 has 4 divisors (see below), whose sum is σ = 667440. Its totient is φ = 664176.

The previous prime is 665803. The next prime is 665813. The reversal of 665807 is 708566.

665807 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 665807 - 2² = 665803 is a prime.

It is a super-2 number, since 2×665807² = 886597922498, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665801) 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, 398 + ... + 1220.

It is an arithmetic number, because the mean of its divisors is an integer number (166860).

2⁶⁶⁵⁸⁰⁷ is an apocalyptic number.

665807 is a deficient number, since it is larger than the sum of its proper divisors (1633).

665807 is an equidigital number, since it uses as much as digits as its factorization.

665807 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1632.

The product of its (nonzero) digits is 10080, while the sum is 32.

The square root of 665807 is about 815.9699749378. The cubic root of 665807 is about 87.3204809218.

The spelling of 665807 in words is "six hundred sixty-five thousand, eight hundred seven".