644023136 has 12 divisors (see below), whose sum is σ = 1267920612. Its totient is φ = 322011552.

The previous prime is 644023033. The next prime is 644023151. The reversal of 644023136 is 631320446.

It is a junction number, because it is equal to n+sod(n) for n = 644023099 and 644023108.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10062830 + ... + 10062893.

It is an arithmetic number, because the mean of its divisors is an integer number (105660051).

Almost surely, 2^644023136 is an apocalyptic number.

It is an amenable number.

644023136 is a deficient number, since it is larger than the sum of its proper divisors (623897476).

644023136 is a wasteful number, since it uses less digits than its factorization.

644023136 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20125733 (or 20125725 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 29.

The square root of 644023136 is about 25377.6109198640. The cubic root of 644023136 is about 863.5758520571.

The spelling of 644023136 in words is "six hundred forty-four million, twenty-three thousand, one hundred thirty-six".