644050720 has 24 divisors (see below), whose sum is σ = 1521570204. Its totient is φ = 257620224.

The previous prime is 644050711. The next prime is 644050751. The reversal of 644050720 is 27050446.

It can be written as a sum of positive squares in 2 ways, for example, as 604963216 + 39087504 = 24596^2 + 6252^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2012499 + ... + 2012818.

Almost surely, 2^644050720 is an apocalyptic number.

It is an amenable number.

644050720 is an abundant number, since it is smaller than the sum of its proper divisors (877519484).

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

644050720 is a wasteful number, since it uses less digits than its factorization.

644050720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4025332 (or 4025324 counting only the distinct ones).

The product of its (nonzero) digits is 6720, while the sum is 28.

The square root of 644050720 is about 25378.1543852188. The cubic root of 644050720 is about 863.5881810843.

The spelling of 644050720 in words is "six hundred forty-four million, fifty thousand, seven hundred twenty".