644304400 has 30 divisors (see below), whose sum is σ = 1547942282. Its totient is φ = 257721600.

The previous prime is 644304379. The next prime is 644304407. The reversal of 644304400 is 4403446.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 222248464 + 422055936 = 14908^2 + 20544^2 .

It is a Harshad number since it is a multiple of its sum of digits (25).

It is not an unprimeable number, because it can be changed into a prime (644304407) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 804981 + ... + 805780.

Almost surely, 2^644304400 is an apocalyptic number.

It is an amenable number.

644304400 is an abundant number, since it is smaller than the sum of its proper divisors (903637882).

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

644304400 is a wasteful number, since it uses less digits than its factorization.

644304400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1610779 (or 1610768 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 25.

The square root of 644304400 is about 25383.1518925448. The cubic root of 644304400 is about 863.7015501539.

Adding to 644304400 its reverse (4403446), we get a palindrome (648707846).

The spelling of 644304400 in words is "six hundred forty-four million, three hundred four thousand, four hundred".