644625740 has 48 divisors (see below), whose sum is σ = 1501839360. Its totient is φ = 230431680.

The previous prime is 644625713. The next prime is 644625757. The reversal of 644625740 is 47526446.

It is a junction number, because it is equal to n+sod(n) for n = 644625694 and 644625703.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11852 + ... + 37811.

It is an arithmetic number, because the mean of its divisors is an integer number (31288320).

Almost surely, 2^644625740 is an apocalyptic number.

It is an amenable number.

644625740 is an abundant number, since it is smaller than the sum of its proper divisors (857213620).

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

644625740 is a wasteful number, since it uses less digits than its factorization.

644625740 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49742 (or 49740 counting only the distinct ones).

The product of its (nonzero) digits is 161280, while the sum is 38.

The square root of 644625740 is about 25389.4808926847. The cubic root of 644625740 is about 863.8451136252.

The spelling of 644625740 in words is "six hundred forty-four million, six hundred twenty-five thousand, seven hundred forty".