644016740 has 24 divisors (see below), whose sum is σ = 1361518200. Its totient is φ = 255876608.

The previous prime is 644016733. The next prime is 644016757. The reversal of 644016740 is 47610446.

It can be written as a sum of positive squares in 4 ways, for example, as 10588516 + 633428224 = 3254^2 + 25168^2 .

It is a super-2 number, since 2×644016740² = 829515122800455200, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 644016697 and 644016706.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 105077 + ... + 111036.

It is an arithmetic number, because the mean of its divisors is an integer number (56729925).

Almost surely, 2^644016740 is an apocalyptic number.

It is an amenable number.

644016740 is an abundant number, since it is smaller than the sum of its proper divisors (717501460).

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

644016740 is a wasteful number, since it uses less digits than its factorization.

644016740 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 216271 (or 216269 counting only the distinct ones).

The product of its (nonzero) digits is 16128, while the sum is 32.

The square root of 644016740 is about 25377.4849029607. The cubic root of 644016740 is about 863.5729932315.

The spelling of 644016740 in words is "six hundred forty-four million, sixteen thousand, seven hundred forty".