644980907 has 2 divisors, whose sum is σ = 644980908. Its totient is φ = 644980906.

The previous prime is 644980883. The next prime is 644980933. The reversal of 644980907 is 709089446.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 644980907 - 2¹⁰ = 644979883 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (644980957) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322490453 + 322490454.

It is an arithmetic number, because the mean of its divisors is an integer number (322490454).

Almost surely, 2^644980907 is an apocalyptic number.

644980907 is a deficient number, since it is larger than the sum of its proper divisors (1).

644980907 is an equidigital number, since it uses as much as digits as its factorization.

644980907 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 435456, while the sum is 47.

The square root of 644980907 is about 25396.4743025484. The cubic root of 644980907 is about 864.0037343196.

The spelling of 644980907 in words is "six hundred forty-four million, nine hundred eighty thousand, nine hundred seven".