644626544 has 20 divisors (see below), whose sum is σ = 1249368696. Its totient is φ = 322208832.

The previous prime is 644626501. The next prime is 644626561. The reversal of 644626544 is 445626446.

It is a congruent number.

It is an unprimeable number.

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, 76022 + ... + 84074.

Almost surely, 2^644626544 is an apocalyptic number.

It is an amenable number.

644626544 is a deficient number, since it is larger than the sum of its proper divisors (604742152).

644626544 is a wasteful number, since it uses less digits than its factorization.

644626544 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13064 (or 13058 counting only the distinct ones).

The product of its digits is 552960, while the sum is 41.

The square root of 644626544 is about 25389.4967260086. The cubic root of 644626544 is about 863.8454727644.

The spelling of 644626544 in words is "six hundred forty-four million, six hundred twenty-six thousand, five hundred forty-four".