644780818486 has 12 divisors (see below), whose sum is σ = 1125076734468. Its totient is φ = 276334636452.

The previous prime is 644780818481. The next prime is 644780818529. The reversal of 644780818486 is 684818087446.

644780818486 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644780818481) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 3289697956 + ... + 3289698151.

It is an arithmetic number, because the mean of its divisors is an integer number (93756394539).

Almost surely, 2^644780818486 is an apocalyptic number.

644780818486 is a deficient number, since it is larger than the sum of its proper divisors (480295915982).

644780818486 is a wasteful number, since it uses less digits than its factorization.

644780818486 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6579396123 (or 6579396116 counting only the distinct ones).

The product of its (nonzero) digits is 66060288, while the sum is 64.

The spelling of 644780818486 in words is "six hundred forty-four billion, seven hundred eighty million, eight hundred eighteen thousand, four hundred eighty-six".