644733337441 has 2 divisors, whose sum is σ = 644733337442. Its totient is φ = 644733337440.

The previous prime is 644733337439. The next prime is 644733337499. The reversal of 644733337441 is 144733337446.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 612807152400 + 31926185041 = 782820^2 + 178679^2 .

It is a cyclic number.

It is not a de Polignac number, because 644733337441 - 2¹ = 644733337439 is a prime.

Together with 644733337439, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (644734337441) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322366668720 + 322366668721.

It is an arithmetic number, because the mean of its divisors is an integer number (322366668721).

Almost surely, 2^644733337441 is an apocalyptic number.

It is an amenable number.

644733337441 is a deficient number, since it is larger than the sum of its proper divisors (1).

644733337441 is an equidigital number, since it uses as much as digits as its factorization.

644733337441 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6096384, while the sum is 49.

The spelling of 644733337441 in words is "six hundred forty-four billion, seven hundred thirty-three million, three hundred thirty-seven thousand, four hundred forty-one".