644980906 has 8 divisors (see below), whose sum is σ = 988056000. Its totient is φ = 315628908.

The previous prime is 644980883. The next prime is 644980907. The reversal of 644980906 is 609089446.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (644980907) 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 3 ways as a sum of consecutive naturals, for example, 3430656 + ... + 3430843.

It is an arithmetic number, because the mean of its divisors is an integer number (123507000).

Almost surely, 2^644980906 is an apocalyptic number.

644980906 is a deficient number, since it is larger than the sum of its proper divisors (343075094).

644980906 is a wasteful number, since it uses less digits than its factorization.

644980906 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6861548.

The product of its (nonzero) digits is 373248, while the sum is 46.

The square root of 644980906 is about 25396.4742828606. The cubic root of 644980906 is about 864.0037338730.

The spelling of 644980906 in words is "six hundred forty-four million, nine hundred eighty thousand, nine hundred six".