644013 has 12 divisors (see below), whose sum is σ = 938080. Its totient is φ = 425736.

The previous prime is 644009. The next prime is 644029. The reversal of 644013 is 310446.

644013 is digitally balanced in base 7, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 644013 - 2² = 644009 is a prime.

It is a Duffinian number.

644013 is strictly pandigital in base 7.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644053) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1248 + ... + 1686.

2⁶⁴⁴⁰¹³ is an apocalyptic number.

It is an amenable number.

644013 is a deficient number, since it is larger than the sum of its proper divisors (294067).

644013 is a wasteful number, since it uses less digits than its factorization.

644013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 608 (or 605 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 18.

The square root of 644013 is about 802.5042055965. The cubic root of 644013 is about 86.3571321552.

Adding to 644013 its reverse (310446), we get a palindrome (954459).

The spelling of 644013 in words is "six hundred forty-four thousand, thirteen".