644023033 has 2 divisors, whose sum is σ = 644023034. Its totient is φ = 644023032.

The previous prime is 644023027. The next prime is 644023151. The reversal of 644023033 is 330320446.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 582353424 + 61669609 = 24132^2 + 7853^2 .

It is a cyclic number.

It is not a de Polignac number, because 644023033 - 2²⁹ = 107152121 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 644022989 and 644023007.

It is not a weakly prime, because it can be changed into another prime (644023333) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322011516 + 322011517.

It is an arithmetic number, because the mean of its divisors is an integer number (322011517).

Almost surely, 2^644023033 is an apocalyptic number.

It is an amenable number.

644023033 is a deficient number, since it is larger than the sum of its proper divisors (1).

644023033 is an equidigital number, since it uses as much as digits as its factorization.

644023033 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5184, while the sum is 25.

The square root of 644023033 is about 25377.6088905161. The cubic root of 644023033 is about 863.5758060193.

Adding to 644023033 its reverse (330320446), we get a palindrome (974343479).

The spelling of 644023033 in words is "six hundred forty-four million, twenty-three thousand, thirty-three".