644640826080 has 48 divisors (see below), whose sum is σ = 2030618603664. Its totient is φ = 171904220160.

The previous prime is 644640826043. The next prime is 644640826097. The reversal of 644640826080 is 80628046446.

It is a tau number, because it is divible by the number of its divisors (48).

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 671500381 + ... + 671501340.

It is an arithmetic number, because the mean of its divisors is an integer number (42304554243).

Almost surely, 2^644640826080 is an apocalyptic number.

644640826080 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

644640826080 is an abundant number, since it is smaller than the sum of its proper divisors (1385977777584).

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

644640826080 is a wasteful number, since it uses less digits than its factorization.

644640826080 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1343001739 (or 1343001731 counting only the distinct ones).

The product of its (nonzero) digits is 1769472, while the sum is 48.

The spelling of 644640826080 in words is "six hundred forty-four billion, six hundred forty million, eight hundred twenty-six thousand, eighty".