644405130 has 24 divisors (see below), whose sum is σ = 1675453572. Its totient is φ = 171841344.

The previous prime is 644405081. The next prime is 644405131. The reversal of 644405130 is 31504446.

644405130 is a `hidden beast` number, since 644 + 4 + 0 + 5 + 13 + 0 = 666.

644405130 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 528218289 + 116186841 = 22983^2 + 10779^2 .

It is a junction number, because it is equal to n+sod(n) for n = 644405094 and 644405103.

It is not an unprimeable number, because it can be changed into a prime (644405131) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3579939 + ... + 3580118.

Almost surely, 2^644405130 is an apocalyptic number.

644405130 is an abundant number, since it is smaller than the sum of its proper divisors (1031048442).

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

644405130 is a wasteful number, since it uses less digits than its factorization.

644405130 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7160070 (or 7160067 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 27.

The square root of 644405130 is about 25385.1360051507. The cubic root of 644405130 is about 863.7465579296.

Adding to 644405130 its reverse (31504446), we get a palindrome (675909576).

The spelling of 644405130 in words is "six hundred forty-four million, four hundred five thousand, one hundred thirty".