644240224 has 24 divisors (see below), whose sum is σ = 1269496368. Its totient is φ = 321828480.

The previous prime is 644240209. The next prime is 644240231. The reversal of 644240224 is 422042446.

It is a junction number, because it is equal to n+sod(n) for n = 644240192 and 644240201.

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, 29269 + ... + 46315.

It is an arithmetic number, because the mean of its divisors is an integer number (52895682).

Almost surely, 2^644240224 is an apocalyptic number.

It is an amenable number.

644240224 is a deficient number, since it is larger than the sum of its proper divisors (625256144).

644240224 is a wasteful number, since it uses less digits than its factorization.

644240224 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18238 (or 18230 counting only the distinct ones).

The product of its (nonzero) digits is 12288, while the sum is 28.

The square root of 644240224 is about 25381.8877154557. The cubic root of 644240224 is about 863.6728728439.

The spelling of 644240224 in words is "six hundred forty-four million, two hundred forty thousand, two hundred twenty-four".