644810316643 has 2 divisors, whose sum is σ = 644810316644. Its totient is φ = 644810316642.

The previous prime is 644810316571. The next prime is 644810316697. The reversal of 644810316643 is 346613018446.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 644810316643 - 2²⁹ = 644273445731 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 644810316593 and 644810316602.

It is not a weakly prime, because it can be changed into another prime (644810316343) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322405158321 + 322405158322.

It is an arithmetic number, because the mean of its divisors is an integer number (322405158322).

Almost surely, 2^644810316643 is an apocalyptic number.

644810316643 is a deficient number, since it is larger than the sum of its proper divisors (1).

644810316643 is an equidigital number, since it uses as much as digits as its factorization.

644810316643 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 995328, while the sum is 46.

The spelling of 644810316643 in words is "six hundred forty-four billion, eight hundred ten million, three hundred sixteen thousand, six hundred forty-three".