644680718451 has 96 divisors (see below), whose sum is σ = 1293975820800. Its totient is φ = 298609597440.

The previous prime is 644680718443. The next prime is 644680718467. The reversal of 644680718451 is 154817086446.

644680718451 is a `hidden beast` number, since 6 + 4 + 46 + 80 + 71 + 8 + 451 = 666.

It is not a de Polignac number, because 644680718451 - 2³ = 644680718443 is a prime.

It is a super-2 number, since 2×644680718451² (a number of 24 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (644680718441) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 1216216 + ... + 1663893.

It is an arithmetic number, because the mean of its divisors is an integer number (13478914800).

Almost surely, 2^644680718451 is an apocalyptic number.

644680718451 is an abundant number, since it is smaller than the sum of its proper divisors (649295102349).

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

644680718451 is a wasteful number, since it uses less digits than its factorization.

644680718451 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2880169 (or 2880166 counting only the distinct ones).

The product of its (nonzero) digits is 5160960, while the sum is 54.

The spelling of 644680718451 in words is "six hundred forty-four billion, six hundred eighty million, seven hundred eighteen thousand, four hundred fifty-one".