644687659830 has 32 divisors (see below), whose sum is σ = 1576443790944. Its totient is φ = 168672997376.

The previous prime is 644687659829. The next prime is 644687659841. The reversal of 644687659830 is 38956786446.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 202730379 + ... + 202733558.

It is an arithmetic number, because the mean of its divisors is an integer number (49263868467).

Almost surely, 2^644687659830 is an apocalyptic number.

644687659830 is an abundant number, since it is smaller than the sum of its proper divisors (931756131114).

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

644687659830 is a wasteful number, since it uses less digits than its factorization.

644687659830 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 405464000.

The product of its (nonzero) digits is 209018880, while the sum is 66.

The spelling of 644687659830 in words is "six hundred forty-four billion, six hundred eighty-seven million, six hundred fifty-nine thousand, eight hundred thirty".