644209283 has 2 divisors, whose sum is σ = 644209284. Its totient is φ = 644209282.

The previous prime is 644209243. The next prime is 644209297. The reversal of 644209283 is 382902446.

It is a happy number.

644209283 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-644209283 is a prime.

It is not a weakly prime, because it can be changed into another prime (644209243) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322104641 + 322104642.

It is an arithmetic number, because the mean of its divisors is an integer number (322104642).

Almost surely, 2^644209283 is an apocalyptic number.

644209283 is a deficient number, since it is larger than the sum of its proper divisors (1).

644209283 is an equidigital number, since it uses as much as digits as its factorization.

644209283 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 82944, while the sum is 38.

The square root of 644209283 is about 25381.2781987039. The cubic root of 644209283 is about 863.6590460501.

The spelling of 644209283 in words is "six hundred forty-four million, two hundred nine thousand, two hundred eighty-three".