644183064 has 128 divisors (see below), whose sum is σ = 2071296000. Its totient is φ = 181688832.

The previous prime is 644183053. The next prime is 644183077. The reversal of 644183064 is 460381446.

644183064 is a `hidden beast` number, since 644 + 1 + 8 + 3 + 0 + 6 + 4 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 116752 + ... + 122144.

It is an arithmetic number, because the mean of its divisors is an integer number (16182000).

Almost surely, 2^644183064 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644183064, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1035648000).

644183064 is an abundant number, since it is smaller than the sum of its proper divisors (1427112936).

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

644183064 is a wasteful number, since it uses less digits than its factorization.

644183064 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5494 (or 5484 counting only the distinct ones).

The product of its (nonzero) digits is 55296, while the sum is 36.

The square root of 644183064 is about 25380.7616906979. The cubic root of 644183064 is about 863.6473290588.

The spelling of 644183064 in words is "six hundred forty-four million, one hundred eighty-three thousand, sixty-four".