644536213 has 2 divisors, whose sum is σ = 644536214. Its totient is φ = 644536212.

The previous prime is 644536201. The next prime is 644536229. The reversal of 644536213 is 312635446.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 499164964 + 145371249 = 22342^2 + 12057^2 .

It is a cyclic number.

It is not a de Polignac number, because 644536213 - 2²⁵ = 610981781 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644536253) 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, 322268106 + 322268107.

It is an arithmetic number, because the mean of its divisors is an integer number (322268107).

Almost surely, 2^644536213 is an apocalyptic number.

It is an amenable number.

644536213 is a deficient number, since it is larger than the sum of its proper divisors (1).

644536213 is an equidigital number, since it uses as much as digits as its factorization.

644536213 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 51840, while the sum is 34.

The square root of 644536213 is about 25387.7177587904. The cubic root of 644536213 is about 863.8051208887.

The spelling of 644536213 in words is "six hundred forty-four million, five hundred thirty-six thousand, two hundred thirteen".