644741560 has 16 divisors (see below), whose sum is σ = 1450668600. Its totient is φ = 257896608.

The previous prime is 644741551. The next prime is 644741561. The reversal of 644741560 is 65147446.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644741561) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8059230 + ... + 8059309.

Almost surely, 2^644741560 is an apocalyptic number.

It is an amenable number.

644741560 is an abundant number, since it is smaller than the sum of its proper divisors (805927040).

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

644741560 is a wasteful number, since it uses less digits than its factorization.

644741560 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16118550 (or 16118546 counting only the distinct ones).

The product of its (nonzero) digits is 80640, while the sum is 37.

The square root of 644741560 is about 25391.7616560963. The cubic root of 644741560 is about 863.8968462525.

The spelling of 644741560 in words is "six hundred forty-four million, seven hundred forty-one thousand, five hundred sixty".