644774487737 has 2 divisors, whose sum is σ = 644774487738. Its totient is φ = 644774487736.

The previous prime is 644774487701. The next prime is 644774487761. The reversal of 644774487737 is 737784477446.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 430210057216 + 214564430521 = 655904^2 + 463211^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-644774487737 is a prime.

It is not a weakly prime, because it can be changed into another prime (644774487787) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322387243868 + 322387243869.

It is an arithmetic number, because the mean of its divisors is an integer number (322387243869).

Almost surely, 2^644774487737 is an apocalyptic number.

It is an amenable number.

644774487737 is a deficient number, since it is larger than the sum of its proper divisors (1).

644774487737 is an equidigital number, since it uses as much as digits as its factorization.

644774487737 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 619573248, while the sum is 68.

The spelling of 644774487737 in words is "six hundred forty-four billion, seven hundred seventy-four million, four hundred eighty-seven thousand, seven hundred thirty-seven".