644026223 has 4 divisors (see below), whose sum is σ = 677922360. Its totient is φ = 610130088.

The previous prime is 644026219. The next prime is 644026277. The reversal of 644026223 is 322620446.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 322620446 = 2 ⋅161310223.

It is a cyclic number.

It is not a de Polignac number, because 644026223 - 2² = 644026219 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644026423) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16948040 + ... + 16948077.

It is an arithmetic number, because the mean of its divisors is an integer number (169480590).

Almost surely, 2^644026223 is an apocalyptic number.

644026223 is a deficient number, since it is larger than the sum of its proper divisors (33896137).

644026223 is a wasteful number, since it uses less digits than its factorization.

644026223 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33896136.

The product of its (nonzero) digits is 13824, while the sum is 29.

The square root of 644026223 is about 25377.6717411192. The cubic root of 644026223 is about 863.5772318494.

Adding to 644026223 its reverse (322620446), we get a palindrome (966646669).

The spelling of 644026223 in words is "six hundred forty-four million, twenty-six thousand, two hundred twenty-three".