644116655 has 32 divisors (see below), whose sum is σ = 1007282304. Its totient is φ = 383717376.

The previous prime is 644116639. The next prime is 644116661. The reversal of 644116655 is 556611446.

It is a happy number.

644116655 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 644116655 - 2⁴ = 644116639 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 33902 + ... + 49371.

It is an arithmetic number, because the mean of its divisors is an integer number (31477572).

Almost surely, 2^644116655 is an apocalyptic number.

644116655 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

644116655 is a deficient number, since it is larger than the sum of its proper divisors (363165649).

644116655 is a wasteful number, since it uses less digits than its factorization.

644116655 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83315.

The product of its digits is 86400, while the sum is 38.

The square root of 644116655 is about 25379.4534023095. The cubic root of 644116655 is about 863.6176501628.

The spelling of 644116655 in words is "six hundred forty-four million, one hundred sixteen thousand, six hundred fifty-five".