644321 has 4 divisors (see below), whose sum is σ = 656532. Its totient is φ = 632112.

The previous prime is 644297. The next prime is 644327. The reversal of 644321 is 123446.

It is a happy number.

644321 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, and also an emirpimes, since its reverse is a distinct semiprime: 123446 = 2 ⋅61723.

It can be written as a sum of positive squares in 2 ways, for example, as 215296 + 429025 = 464^2 + 655^2 .

It is a cyclic number.

It is not a de Polignac number, because 644321 - 2⁶ = 644257 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a nialpdrome in base 10.

It is a junction number, because it is equal to n+sod(n) for n = 644293 and 644302.

It is not an unprimeable number, because it can be changed into a prime (644327) 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, 6026 + ... + 6131.

It is an arithmetic number, because the mean of its divisors is an integer number (164133).

2⁶⁴⁴³²¹ is an apocalyptic number.

It is an amenable number.

644321 is a deficient number, since it is larger than the sum of its proper divisors (12211).

644321 is a wasteful number, since it uses less digits than its factorization.

644321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12210.

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

The square root of 644321 is about 802.6960819638. The cubic root of 644321 is about 86.3708967622.

Adding to 644321 its reverse (123446), we get a palindrome (767767).

The spelling of 644321 in words is "six hundred forty-four thousand, three hundred twenty-one".