644530040 has 64 divisors (see below), whose sum is σ = 1808040960. Its totient is φ = 200891520.

The previous prime is 644530039. The next prime is 644530049. The reversal of 644530040 is 40035446.

It is a junction number, because it is equal to n+sod(n) for n = 644529991 and 644530009.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644530049) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 101552 + ... + 107711.

It is an arithmetic number, because the mean of its divisors is an integer number (28250640).

Almost surely, 2^644530040 is an apocalyptic number.

It is an amenable number.

644530040 is an abundant number, since it is smaller than the sum of its proper divisors (1163510920).

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

644530040 is a wasteful number, since it uses less digits than its factorization.

644530040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 209292 (or 209288 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 26.

The square root of 644530040 is about 25387.5961839635. The cubic root of 644530040 is about 863.8023632024.

Adding to 644530040 its reverse (40035446), we get a palindrome (684565486).

The spelling of 644530040 in words is "six hundred forty-four million, five hundred thirty thousand, forty".