644288804 has 12 divisors (see below), whose sum is σ = 1132346124. Its totient is φ = 320761344.

The previous prime is 644288789. The next prime is 644288819. The reversal of 644288804 is 408882446.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (644288789) and next prime (644288819).

It can be written as a sum of positive squares in 2 ways, for example, as 386043904 + 258244900 = 19648^2 + 16070^2 .

It is a hoax number, since the sum of its digits (44) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 344717 + ... + 346580.

It is an arithmetic number, because the mean of its divisors is an integer number (94362177).

Almost surely, 2^644288804 is an apocalyptic number.

It is an amenable number.

644288804 is a deficient number, since it is larger than the sum of its proper divisors (488057320).

644288804 is a wasteful number, since it uses less digits than its factorization.

644288804 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 691534 (or 691532 counting only the distinct ones).

The product of its (nonzero) digits is 393216, while the sum is 44.

The square root of 644288804 is about 25382.8446790347. The cubic root of 644288804 is about 863.6945811922.

The spelling of 644288804 in words is "six hundred forty-four million, two hundred eighty-eight thousand, eight hundred four".