644368271040 has 672 divisors, whose sum is σ = 2497596768576. Its totient is φ = 157182197760.

The previous prime is 644368270991. The next prime is 644368271059. The reversal of 644368271040 is 40172863446.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 114226620 + ... + 114232260.

It is an arithmetic number, because the mean of its divisors is an integer number (3716661858).

Almost surely, 2^644368271040 is an apocalyptic number.

644368271040 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644368271040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1248798384288).

644368271040 is an abundant number, since it is smaller than the sum of its proper divisors (1853228497536).

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

644368271040 is a wasteful number, since it uses less digits than its factorization.

644368271040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5799 (or 5777 counting only the distinct ones).

The product of its (nonzero) digits is 774144, while the sum is 45.

The spelling of 644368271040 in words is "six hundred forty-four billion, three hundred sixty-eight million, two hundred seventy-one thousand, forty".