644087808 has 304 divisors, whose sum is σ = 2348805760. Its totient is φ = 169869312.

The previous prime is 644087803. The next prime is 644087809. The reversal of 644087808 is 808780446.

It is not an unprimeable number, because it can be changed into a prime (644087803) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 49545210 + ... + 49545222.

Almost surely, 2^644087808 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 644087808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1174402880).

644087808 is an abundant number, since it is smaller than the sum of its proper divisors (1704717952).

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

644087808 is an frugal number, since it uses more digits than its factorization.

644087808 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65 (or 25 counting only the distinct ones).

The product of its (nonzero) digits is 344064, while the sum is 45.

The square root of 644087808 is about 25378.8850818944. The cubic root of 644087808 is about 863.6047574929.

The spelling of 644087808 in words is "six hundred forty-four million, eighty-seven thousand, eight hundred eight".