644328280 has 32 divisors (see below), whose sum is σ = 1471382640. Its totient is φ = 253883520.

The previous prime is 644328263. The next prime is 644328281. The reversal of 644328280 is 82823446.

It is a Smith number, since the sum of its digits (37) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644328281) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 117531 + ... + 122890.

Almost surely, 2^644328280 is an apocalyptic number.

It is an amenable number.

644328280 is an abundant number, since it is smaller than the sum of its proper divisors (827054360).

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

644328280 is a wasteful number, since it uses less digits than its factorization.

644328280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 240499 (or 240495 counting only the distinct ones).

The product of its (nonzero) digits is 73728, while the sum is 37.

The square root of 644328280 is about 25383.6222789420. The cubic root of 644328280 is about 863.7122205442.

The spelling of 644328280 in words is "six hundred forty-four million, three hundred twenty-eight thousand, two hundred eighty".