644000215138 has 16 divisors (see below), whose sum is σ = 1104038717184. Its totient is φ = 275990505120.

The previous prime is 644000215121. The next prime is 644000215151. The reversal of 644000215138 is 831512000446.

644000215138 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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, 373683 + ... + 1194838.

It is an arithmetic number, because the mean of its divisors is an integer number (69002419824).

Almost surely, 2^644000215138 is an apocalyptic number.

644000215138 is a deficient number, since it is larger than the sum of its proper divisors (460038502046).

644000215138 is a wasteful number, since it uses less digits than its factorization.

644000215138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1597857.

The product of its (nonzero) digits is 23040, while the sum is 34.

The spelling of 644000215138 in words is "six hundred forty-four billion, two hundred fifteen thousand, one hundred thirty-eight".