644501610 has 112 divisors (see below), whose sum is σ = 1751772960. Its totient is φ = 170644320.

The previous prime is 644501593. The next prime is 644501621. The reversal of 644501610 is 16105446.

644501610 is a `hidden beast` number, since 6 + 4 + 45 + 0 + 1 + 610 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

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 55 ways as a sum of consecutive naturals, for example, 1537981 + ... + 1538399.

It is an arithmetic number, because the mean of its divisors is an integer number (15640830).

Almost surely, 2^644501610 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644501610, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (875886480).

644501610 is an abundant number, since it is smaller than the sum of its proper divisors (1107271350).

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

644501610 is a wasteful number, since it uses less digits than its factorization.

644501610 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 655 (or 640 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 27.

The square root of 644501610 is about 25387.0362586892. The cubic root of 644501610 is about 863.7896623399.

The spelling of 644501610 in words is "six hundred forty-four million, five hundred one thousand, six hundred ten".