644507320458 has 16 divisors (see below), whose sum is σ = 1310146029216. Its totient is φ = 211313875440.

The previous prime is 644507320441. The next prime is 644507320459. The reversal of 644507320458 is 854023705446.

It is a super-2 number, since 2×644507320458² (a number of 24 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (644507320459) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 880474116 + ... + 880474847.

It is an arithmetic number, because the mean of its divisors is an integer number (81884126826).

Almost surely, 2^644507320458 is an apocalyptic number.

644507320458 is an abundant number, since it is smaller than the sum of its proper divisors (665638708758).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

644507320458 is a wasteful number, since it uses less digits than its factorization.

644507320458 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1760949029.

The product of its (nonzero) digits is 3225600, while the sum is 48.

The spelling of 644507320458 in words is "six hundred forty-four billion, five hundred seven million, three hundred twenty thousand, four hundred fifty-eight".