644883907 has 2 divisors, whose sum is σ = 644883908. Its totient is φ = 644883906.

The previous prime is 644883859. The next prime is 644883929. The reversal of 644883907 is 709388446.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-644883907 is a prime.

It is not a weakly prime, because it can be changed into another prime (644883307) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322441953 + 322441954.

It is an arithmetic number, because the mean of its divisors is an integer number (322441954).

Almost surely, 2^644883907 is an apocalyptic number.

644883907 is a deficient number, since it is larger than the sum of its proper divisors (1).

644883907 is an equidigital number, since it uses as much as digits as its factorization.

644883907 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1161216, while the sum is 49.

The square root of 644883907 is about 25394.5645168410. The cubic root of 644883907 is about 863.9604190508.

The spelling of 644883907 in words is "six hundred forty-four million, eight hundred eighty-three thousand, nine hundred seven".