644246644 has 6 divisors (see below), whose sum is σ = 1127431634. Its totient is φ = 322123320.

The previous prime is 644246639. The next prime is 644246651. The reversal of 644246644 is 446642446.

It is a happy number.

644246644 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 636956644 + 7290000 = 25238^2 + 2700^2 .

It is a junction number, because it is equal to n+sod(n) for n = 644246597 and 644246606.

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, 80530827 + ... + 80530834.

Almost surely, 2^644246644 is an apocalyptic number.

It is an amenable number.

644246644 is a deficient number, since it is larger than the sum of its proper divisors (483184990).

644246644 is a wasteful number, since it uses less digits than its factorization.

644246644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 161061665 (or 161061663 counting only the distinct ones).

The product of its digits is 442368, while the sum is 40.

The square root of 644246644 is about 25382.0141832755. The cubic root of 644246644 is about 863.6757417331.

The spelling of 644246644 in words is "six hundred forty-four million, two hundred forty-six thousand, six hundred forty-four".