644189268537 has 12 divisors (see below), whose sum is σ = 962581666020. Its totient is φ = 414650563488.

The previous prime is 644189268523. The next prime is 644189268559. The reversal of 644189268537 is 735862981446.

644189268537 is a `hidden beast` number, since 6 + 4 + 4 + 1 + 8 + 92 + 6 + 8 + 537 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 445924786176 + 198264482361 = 667776^2 + 445269^2 .

It is a de Polignac number, because none of the positive numbers 2^k-644189268537 is a prime.

It is not an unprimeable number, because it can be changed into a prime (644189268577) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1234078798 + ... + 1234079319.

It is an arithmetic number, because the mean of its divisors is an integer number (80215138835).

Almost surely, 2^644189268537 is an apocalyptic number.

It is an amenable number.

644189268537 is a deficient number, since it is larger than the sum of its proper divisors (318392397483).

644189268537 is a wasteful number, since it uses less digits than its factorization.

644189268537 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2468158152 (or 2468158149 counting only the distinct ones).

The product of its digits is 69672960, while the sum is 63.

The spelling of 644189268537 in words is "six hundred forty-four billion, one hundred eighty-nine million, two hundred sixty-eight thousand, five hundred thirty-seven".