644169233 has 2 divisors, whose sum is σ = 644169234. Its totient is φ = 644169232.

The previous prime is 644169221. The next prime is 644169247. The reversal of 644169233 is 332961446.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 485232784 + 158936449 = 22028^2 + 12607^2 .

It is a cyclic number.

It is not a de Polignac number, because 644169233 - 2¹⁴ = 644152849 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (644169203) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322084616 + 322084617.

It is an arithmetic number, because the mean of its divisors is an integer number (322084617).

Almost surely, 2^644169233 is an apocalyptic number.

It is an amenable number.

644169233 is a deficient number, since it is larger than the sum of its proper divisors (1).

644169233 is an equidigital number, since it uses as much as digits as its factorization.

644169233 is an evil number, because the sum of its binary digits is even.

The product of its digits is 93312, while the sum is 38.

The square root of 644169233 is about 25380.4892190832. The cubic root of 644169233 is about 863.6411480044.

The spelling of 644169233 in words is "six hundred forty-four million, one hundred sixty-nine thousand, two hundred thirty-three".