644353616 has 20 divisors (see below), whose sum is σ = 1249518612. Its totient is φ = 321897216.

The previous prime is 644353571. The next prime is 644353643. The reversal of 644353616 is 616353446.

It can be written as a sum of positive squares in 2 ways, for example, as 368793616 + 275560000 = 19204^2 + 16600^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 644353616.

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 in 3 ways as a sum of consecutive naturals, for example, 2210 + ... + 35966.

Almost surely, 2^644353616 is an apocalyptic number.

It is an amenable number.

644353616 is a deficient number, since it is larger than the sum of its proper divisors (605164996).

644353616 is a wasteful number, since it uses less digits than its factorization.

644353616 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34958 (or 34952 counting only the distinct ones).

The product of its digits is 155520, while the sum is 38.

The square root of 644353616 is about 25384.1213359848. The cubic root of 644353616 is about 863.7235412362.

The spelling of 644353616 in words is "six hundred forty-four million, three hundred fifty-three thousand, six hundred sixteen".