644420010321065 has 12 divisors (see below), whose sum is σ = 849995319399492. Its totient is φ = 468669098414880.

The previous prime is 644420010321041. The next prime is 644420010321083. The reversal of 644420010321065 is 560123010024446.

It can be written as a sum of positive squares in 2 ways, for example, as 150594326369344 + 493825683951721 = 12271688^2 + 22222189^2 .

It is not a de Polignac number, because 644420010321065 - 2¹⁸ = 644420010058921 is a prime.

It is a super-2 number, since 2×644420010321065² (a number of 30 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 532578520322 + ... + 532578521531.

It is an arithmetic number, because the mean of its divisors is an integer number (70832943283291).

Almost surely, 2^{644420010321065} is an apocalyptic number.

It is an amenable number.

644420010321065 is a deficient number, since it is larger than the sum of its proper divisors (205575309078427).

644420010321065 is a wasteful number, since it uses less digits than its factorization.

644420010321065 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1065157041880 (or 1065157041869 counting only the distinct ones).

The product of its (nonzero) digits is 138240, while the sum is 38.

The spelling of 644420010321065 in words is "six hundred forty-four trillion, four hundred twenty billion, ten million, three hundred twenty-one thousand, sixty-five".