644106884 has 24 divisors (see below), whose sum is σ = 1167679800. Its totient is φ = 310661120.

The previous prime is 644106877. The next prime is 644106887. The reversal of 644106884 is 488601446.

It can be written as a sum of positive squares in 4 ways, for example, as 109202500 + 534904384 = 10450^2 + 23128^2 .

It is a Harshad number since it is a multiple of its sum of digits (41).

It is not an unprimeable number, because it can be changed into a prime (644106887) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7469 + ... + 36660.

It is an arithmetic number, because the mean of its divisors is an integer number (48653325).

Almost surely, 2^644106884 is an apocalyptic number.

It is an amenable number.

644106884 is a deficient number, since it is larger than the sum of its proper divisors (523572916).

644106884 is a wasteful number, since it uses less digits than its factorization.

644106884 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 44263 (or 44261 counting only the distinct ones).

The product of its (nonzero) digits is 147456, while the sum is 41.

The square root of 644106884 is about 25379.2609033439. The cubic root of 644106884 is about 863.6132832257.

The spelling of 644106884 in words is "six hundred forty-four million, one hundred six thousand, eight hundred eighty-four".