644331676 has 12 divisors (see below), whose sum is σ = 1132421472. Its totient is φ = 320782688.

The previous prime is 644331631. The next prime is 644331679. The reversal of 644331676 is 676133446.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644331679) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 344740 + ... + 346603.

It is an arithmetic number, because the mean of its divisors is an integer number (94368456).

Almost surely, 2^644331676 is an apocalyptic number.

It is an amenable number.

644331676 is a deficient number, since it is larger than the sum of its proper divisors (488089796).

644331676 is a wasteful number, since it uses less digits than its factorization.

644331676 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 691580 (or 691578 counting only the distinct ones).

The product of its digits is 217728, while the sum is 40.

The square root of 644331676 is about 25383.6891723800. The cubic root of 644331676 is about 863.7137379703.

The spelling of 644331676 in words is "six hundred forty-four million, three hundred thirty-one thousand, six hundred seventy-six".