644664610 has 16 divisors (see below), whose sum is σ = 1161261432. Its totient is φ = 257673600.

The previous prime is 644664571. The next prime is 644664611. The reversal of 644664610 is 16466446.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 635897089 + 8767521 = 25217^2 + 2961^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 644664610.

It is not an unprimeable number, because it can be changed into a prime (644664611) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9531 + ... + 37150.

Almost surely, 2^644664610 is an apocalyptic number.

644664610 is a deficient number, since it is larger than the sum of its proper divisors (516596822).

644664610 is a wasteful number, since it uses less digits than its factorization.

644664610 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48069.

The product of its (nonzero) digits is 82944, while the sum is 37.

The square root of 644664610 is about 25390.2463556382. The cubic root of 644664610 is about 863.8624761466.

The spelling of 644664610 in words is "six hundred forty-four million, six hundred sixty-four thousand, six hundred ten".