644631530 has 16 divisors (see below), whose sum is σ = 1179359784. Its totient is φ = 253625280.

The previous prime is 644631521. The next prime is 644631569. The reversal of 644631530 is 35136446.

It can be written as a sum of positive squares in 4 ways, for example, as 489604129 + 155027401 = 22127^2 + 12451^2 .

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, 527777 + ... + 528996.

Almost surely, 2^644631530 is an apocalyptic number.

644631530 is a deficient number, since it is larger than the sum of its proper divisors (534728254).

644631530 is a wasteful number, since it uses less digits than its factorization.

644631530 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1056841.

The product of its (nonzero) digits is 25920, while the sum is 32.

The square root of 644631530 is about 25389.5949160281. The cubic root of 644631530 is about 863.8476999570.

Adding to 644631530 its reverse (35136446), we get a palindrome (679767976).

The spelling of 644631530 in words is "six hundred forty-four million, six hundred thirty-one thousand, five hundred thirty".