644435206366 has 32 divisors (see below), whose sum is σ = 1118285160192. Its totient is φ = 272816626560.

The previous prime is 644435206313. The next prime is 644435206369. The reversal of 644435206366 is 663602534446.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644435206369) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 100075 + ... + 1139686.

It is an arithmetic number, because the mean of its divisors is an integer number (34946411256).

Almost surely, 2^644435206366 is an apocalyptic number.

644435206366 is a deficient number, since it is larger than the sum of its proper divisors (473849953826).

644435206366 is a wasteful number, since it uses less digits than its factorization.

644435206366 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1240224.

The product of its (nonzero) digits is 7464960, while the sum is 49.

The spelling of 644435206366 in words is "six hundred forty-four billion, four hundred thirty-five million, two hundred six thousand, three hundred sixty-six".