644011006 has 4 divisors (see below), whose sum is σ = 966016512. Its totient is φ = 322005502.

The previous prime is 644010989. The next prime is 644011087. The reversal of 644011006 is 600110446.

It is a semiprime because it is the product of two primes.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 161002750 + ... + 161002753.

It is an arithmetic number, because the mean of its divisors is an integer number (241504128).

Almost surely, 2^644011006 is an apocalyptic number.

644011006 is a deficient number, since it is larger than the sum of its proper divisors (322005506).

644011006 is a wasteful number, since it uses less digits than its factorization.

644011006 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 322005505.

The product of its (nonzero) digits is 576, while the sum is 22.

The square root of 644011006 is about 25377.3719285508. The cubic root of 644011006 is about 863.5704302846.

The spelling of 644011006 in words is "six hundred forty-four million, eleven thousand, six".