665645 has 8 divisors (see below), whose sum is σ = 811104. Its totient is φ = 524304.

The previous prime is 665633. The next prime is 665659. The reversal of 665645 is 546566.

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

It is a cyclic number.

It is not a de Polignac number, because 665645 - 2⁴ = 665629 is a prime.

It is a super-3 number, since 3×665645³ = 884808481839633375, which contains 333 as substring.

It is a Duffinian number.

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 665645.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 659 + ... + 1328.

It is an arithmetic number, because the mean of its divisors is an integer number (101388).

2⁶⁶⁵⁶⁴⁵ is an apocalyptic number.

It is an amenable number.

665645 is a deficient number, since it is larger than the sum of its proper divisors (145459).

665645 is a wasteful number, since it uses less digits than its factorization.

665645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2059.

The product of its digits is 21600, while the sum is 32.

The square root of 665645 is about 815.8707005402. The cubic root of 665645 is about 87.3133982560.

The spelling of 665645 in words is "six hundred sixty-five thousand, six hundred forty-five".