644821327 has 2 divisors, whose sum is σ = 644821328. Its totient is φ = 644821326.

The previous prime is 644821321. The next prime is 644821357. The reversal of 644821327 is 723128446.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-644821327 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644821321) 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, 322410663 + 322410664.

It is an arithmetic number, because the mean of its divisors is an integer number (322410664).

Almost surely, 2^644821327 is an apocalyptic number.

644821327 is a deficient number, since it is larger than the sum of its proper divisors (1).

644821327 is an equidigital number, since it uses as much as digits as its factorization.

644821327 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 64512, while the sum is 37.

The square root of 644821327 is about 25393.3323335083. The cubic root of 644821327 is about 863.9324716992.

The spelling of 644821327 in words is "six hundred forty-four million, eight hundred twenty-one thousand, three hundred twenty-seven".