644613 has 16 divisors (see below), whose sum is σ = 929280. Its totient is φ = 396144.

The previous prime is 644599. The next prime is 644617. The reversal of 644613 is 316446.

It is not a de Polignac number, because 644613 - 2⁴ = 644597 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644617) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2320 + ... + 2582.

It is an arithmetic number, because the mean of its divisors is an integer number (58080).

2⁶⁴⁴⁶¹³ is an apocalyptic number.

It is an amenable number.

644613 is a deficient number, since it is larger than the sum of its proper divisors (284667).

644613 is a wasteful number, since it uses less digits than its factorization.

644613 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 328.

The product of its digits is 1728, while the sum is 24.

The square root of 644613 is about 802.8779483832. The cubic root of 644613 is about 86.3839422747.

The spelling of 644613 in words is "six hundred forty-four thousand, six hundred thirteen".