644290817443 has 16 divisors (see below), whose sum is σ = 798678173440. Its totient is φ = 506101149216.

The previous prime is 644290817441. The next prime is 644290817447. The reversal of 644290817443 is 344718092446.

It is not a de Polignac number, because 644290817443 - 2¹ = 644290817441 is a prime.

It is a super-2 number, since 2×644290817443² (a number of 24 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (644290817441) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 25455405 + ... + 25480702.

It is an arithmetic number, because the mean of its divisors is an integer number (49917385840).

Almost surely, 2^644290817443 is an apocalyptic number.

644290817443 is a deficient number, since it is larger than the sum of its proper divisors (154387355997).

644290817443 is a wasteful number, since it uses less digits than its factorization.

644290817443 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50936266.

The product of its (nonzero) digits is 4644864, while the sum is 52.

The spelling of 644290817443 in words is "six hundred forty-four billion, two hundred ninety million, eight hundred seventeen thousand, four hundred forty-three".