644231 has 4 divisors (see below), whose sum is σ = 736272. Its totient is φ = 552192.

The previous prime is 644227. The next prime is 644239. The reversal of 644231 is 132446.

It is a happy number.

644231 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 644231 - 2² = 644227 is a prime.

It is a super-2 number, since 2×644231² = 830067162722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644239) 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, 46010 + ... + 46023.

It is an arithmetic number, because the mean of its divisors is an integer number (184068).

2⁶⁴⁴²³¹ is an apocalyptic number.

644231 is a deficient number, since it is larger than the sum of its proper divisors (92041).

644231 is an equidigital number, since it uses as much as digits as its factorization.

644231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 92040.

The product of its digits is 576, while the sum is 20.

The square root of 644231 is about 802.6400189375. The cubic root of 644231 is about 86.3668750905.

Adding to 644231 its reverse (132446), we get a palindrome (776677).

The spelling of 644231 in words is "six hundred forty-four thousand, two hundred thirty-one".