644347523 has 2 divisors, whose sum is σ = 644347524. Its totient is φ = 644347522.

The previous prime is 644347441. The next prime is 644347547. The reversal of 644347523 is 325743446.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 644347523 - 2¹⁶ = 644281987 is a prime.

It is not a weakly prime, because it can be changed into another prime (644346523) 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 as a sum of consecutive naturals, namely, 322173761 + 322173762.

It is an arithmetic number, because the mean of its divisors is an integer number (322173762).

Almost surely, 2^644347523 is an apocalyptic number.

644347523 is a deficient number, since it is larger than the sum of its proper divisors (1).

644347523 is an equidigital number, since it uses as much as digits as its factorization.

644347523 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 241920, while the sum is 38.

The square root of 644347523 is about 25384.0013197289. The cubic root of 644347523 is about 863.7208187745.

The spelling of 644347523 in words is "six hundred forty-four million, three hundred forty-seven thousand, five hundred twenty-three".