644162064 has 160 divisors (see below), whose sum is σ = 2072367360. Its totient is φ = 167878656.

The previous prime is 644162063. The next prime is 644162083. The reversal of 644162064 is 460261446.

It is not an unprimeable number, because it can be changed into a prime (644162063) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 387924 + ... + 389580.

It is an arithmetic number, because the mean of its divisors is an integer number (12952296).

Almost surely, 2^644162064 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 644162064, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1036183680).

644162064 is an abundant number, since it is smaller than the sum of its proper divisors (1428205296).

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

644162064 is a wasteful number, since it uses less digits than its factorization.

644162064 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1777 (or 1771 counting only the distinct ones).

The product of its (nonzero) digits is 27648, while the sum is 33.

The square root of 644162064 is about 25380.3479881581. The cubic root of 644162064 is about 863.6379441536.

The spelling of 644162064 in words is "six hundred forty-four million, one hundred sixty-two thousand, sixty-four".