644133604 has 48 divisors (see below), whose sum is σ = 1216782000. Its totient is φ = 298303488.

The previous prime is 644133601. The next prime is 644133617. The reversal of 644133604 is 406331446.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 12616704 + 631516900 = 3552^2 + 25130^2 .

It is not an unprimeable number, because it can be changed into a prime (644133601) 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, 1434372 + ... + 1434820.

It is an arithmetic number, because the mean of its divisors is an integer number (25349625).

Almost surely, 2^644133604 is an apocalyptic number.

It is an amenable number.

644133604 is a deficient number, since it is larger than the sum of its proper divisors (572648396).

644133604 is a wasteful number, since it uses less digits than its factorization.

644133604 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 577 (or 541 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 31.

The square root of 644133604 is about 25379.7873119536. The cubic root of 644133604 is about 863.6252250470.

The spelling of 644133604 in words is "six hundred forty-four million, one hundred thirty-three thousand, six hundred four".