644459 has 4 divisors (see below), whose sum is σ = 665280. Its totient is φ = 623640.

The previous prime is 644447. The next prime is 644489. The reversal of 644459 is 954446.

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 644459 - 2⁴ = 644443 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644489) 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, 10364 + ... + 10425.

It is an arithmetic number, because the mean of its divisors is an integer number (166320).

2⁶⁴⁴⁴⁵⁹ is an apocalyptic number.

644459 is a deficient number, since it is larger than the sum of its proper divisors (20821).

644459 is a wasteful number, since it uses less digits than its factorization.

644459 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20820.

The product of its digits is 17280, while the sum is 32.

The square root of 644459 is about 802.7820376665. The cubic root of 644459 is about 86.3770625983.

The spelling of 644459 in words is "six hundred forty-four thousand, four hundred fifty-nine".