644568329 has 2 divisors, whose sum is σ = 644568330. Its totient is φ = 644568328.

The previous prime is 644568299. The next prime is 644568359. The reversal of 644568329 is 923865446.

It is a balanced prime because it is at equal distance from previous prime (644568299) and next prime (644568359).

It can be written as a sum of positive squares in only one way, i.e., 468289600 + 176278729 = 21640^2 + 13277^2 .

It is a cyclic number.

It is not a de Polignac number, because 644568329 - 2²⁰ = 643519753 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (644568359) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322284164 + 322284165.

It is an arithmetic number, because the mean of its divisors is an integer number (322284165).

Almost surely, 2^644568329 is an apocalyptic number.

It is an amenable number.

644568329 is a deficient number, since it is larger than the sum of its proper divisors (1).

644568329 is an equidigital number, since it uses as much as digits as its factorization.

644568329 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1244160, while the sum is 47.

The square root of 644568329 is about 25388.3502614880. The cubic root of 644568329 is about 863.8194678997.

The spelling of 644568329 in words is "six hundred forty-four million, five hundred sixty-eight thousand, three hundred twenty-nine".