644838 has 8 divisors (see below), whose sum is σ = 1289688. Its totient is φ = 214944.

The previous prime is 644837. The next prime is 644843. The reversal of 644838 is 838446.

It is a sphenic number, since it is the product of 3 distinct primes.

644838 is an admirable number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 644799 and 644808.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644837) 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, 53731 + ... + 53742.

It is an arithmetic number, because the mean of its divisors is an integer number (161211).

2⁶⁴⁴⁸³⁸ is an apocalyptic number.

644838 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

644838 is a wasteful number, since it uses less digits than its factorization.

644838 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 107478.

The product of its digits is 18432, while the sum is 33.

The square root of 644838 is about 803.0180570822. The cubic root of 644838 is about 86.3939917804.

It can be divided in two parts, 6 and 44838, that added together give a palindrome (44844).

The spelling of 644838 in words is "six hundred forty-four thousand, eight hundred thirty-eight".