644938695186 has 16 divisors (see below), whose sum is σ = 1289908861824. Its totient is φ = 214974319824.

The previous prime is 644938695139. The next prime is 644938695197. The reversal of 644938695186 is 681596839446.

It is a self number, because there is not a number n which added to its sum of digits gives 644938695186.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1040605 + ... + 1540368.

It is an arithmetic number, because the mean of its divisors is an integer number (80619303864).

Almost surely, 2^644938695186 is an apocalyptic number.

644938695186 is an abundant number, since it is smaller than the sum of its proper divisors (644970166638).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

644938695186 is a wasteful number, since it uses less digits than its factorization.

644938695186 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2622625.

The product of its digits is 268738560, while the sum is 69.

The spelling of 644938695186 in words is "six hundred forty-four billion, nine hundred thirty-eight million, six hundred ninety-five thousand, one hundred eighty-six".