665543 has 4 divisors (see below), whose sum is σ = 667800. Its totient is φ = 663288.

The previous prime is 665527. The next prime is 665549. The reversal of 665543 is 345566.

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 665543 - 2⁴ = 665527 is a prime.

It is a Duffinian number.

It is a plaindrome in base 14.

It is a nialpdrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665549) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 605 + ... + 1302.

It is an arithmetic number, because the mean of its divisors is an integer number (166950).

2⁶⁶⁵⁵⁴³ is an apocalyptic number.

665543 is a deficient number, since it is larger than the sum of its proper divisors (2257).

665543 is a wasteful number, since it uses less digits than its factorization.

665543 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2256.

The product of its digits is 10800, while the sum is 29.

The square root of 665543 is about 815.8081882403. The cubic root of 665543 is about 87.3089382102.

The spelling of 665543 in words is "six hundred sixty-five thousand, five hundred forty-three".