645559 has 4 divisors (see below), whose sum is σ = 660616. Its totient is φ = 630504.

The previous prime is 645529. The next prime is 645571. The reversal of 645559 is 955546.

It is a happy number.

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 645559 - 2⁵ = 645527 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645529) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7464 + ... + 7549.

It is an arithmetic number, because the mean of its divisors is an integer number (165154).

2⁶⁴⁵⁵⁵⁹ is an apocalyptic number.

645559 is a deficient number, since it is larger than the sum of its proper divisors (15057).

645559 is a wasteful number, since it uses less digits than its factorization.

645559 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15056.

The product of its digits is 27000, while the sum is 34.

The square root of 645559 is about 803.4668630379. The cubic root of 645559 is about 86.4261791240.

The spelling of 645559 in words is "six hundred forty-five thousand, five hundred fifty-nine".