644360388 has 36 divisors (see below), whose sum is σ = 1748979792. Its totient is φ = 184102800.

The previous prime is 644360377. The next prime is 644360399. The reversal of 644360388 is 883063446.

It is an interprime number because it is at equal distance from previous prime (644360377) and next prime (644360399).

It is a Harshad number since it is a multiple of its sum of digits (42).

It is an unprimeable number.

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 11 ways as a sum of consecutive naturals, for example, 547338 + ... + 548513.

It is an arithmetic number, because the mean of its divisors is an integer number (48582772).

Almost surely, 2^644360388 is an apocalyptic number.

It is an amenable number.

644360388 is an abundant number, since it is smaller than the sum of its proper divisors (1104619404).

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

644360388 is a wasteful number, since it uses less digits than its factorization.

644360388 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1095872 (or 1095863 counting only the distinct ones).

The product of its (nonzero) digits is 331776, while the sum is 42.

The square root of 644360388 is about 25384.2547261093. The cubic root of 644360388 is about 863.7265670672.

The spelling of 644360388 in words is "six hundred forty-four million, three hundred sixty thousand, three hundred eighty-eight".