644906598361 has 2 divisors, whose sum is σ = 644906598362. Its totient is φ = 644906598360.

The previous prime is 644906598283. The next prime is 644906598409. The reversal of 644906598361 is 163895609446.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 323014902336 + 321891696025 = 568344^2 + 567355^2 .

It is a cyclic number.

It is not a de Polignac number, because 644906598361 - 2¹⁹ = 644906074073 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 644906598361.

It is not a weakly prime, because it can be changed into another prime (644906598761) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322453299180 + 322453299181.

It is an arithmetic number, because the mean of its divisors is an integer number (322453299181).

Almost surely, 2^644906598361 is an apocalyptic number.

It is an amenable number.

644906598361 is a deficient number, since it is larger than the sum of its proper divisors (1).

644906598361 is an equidigital number, since it uses as much as digits as its factorization.

644906598361 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 33592320, while the sum is 61.

The spelling of 644906598361 in words is "six hundred forty-four billion, nine hundred six million, five hundred ninety-eight thousand, three hundred sixty-one".