644445436 has 24 divisors (see below), whose sum is σ = 1154265840. Its totient is φ = 314725632.

The previous prime is 644445427. The next prime is 644445443. The reversal of 644445436 is 634544446.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 28356 + ... + 45748.

It is an arithmetic number, because the mean of its divisors is an integer number (48094410).

Almost surely, 2^644445436 is an apocalyptic number.

It is an amenable number.

644445436 is a deficient number, since it is larger than the sum of its proper divisors (509820404).

644445436 is a wasteful number, since it uses less digits than its factorization.

644445436 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17613 (or 17611 counting only the distinct ones).

The product of its digits is 552960, while the sum is 40.

The square root of 644445436 is about 25385.9298825156. The cubic root of 644445436 is about 863.7645659814.

The spelling of 644445436 in words is "six hundred forty-four million, four hundred forty-five thousand, four hundred thirty-six".