644235584161 has 16 divisors (see below), whose sum is σ = 739110282624. Its totient is φ = 556264122624.

The previous prime is 644235584143. The next prime is 644235584207. The reversal of 644235584161 is 161485532446.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-644235584161 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644235584131) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8905981 + ... + 8978026.

It is an arithmetic number, because the mean of its divisors is an integer number (46194392664).

Almost surely, 2^644235584161 is an apocalyptic number.

It is an amenable number.

644235584161 is a deficient number, since it is larger than the sum of its proper divisors (94874698463).

644235584161 is a wasteful number, since it uses less digits than its factorization.

644235584161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17884200.

The product of its digits is 2764800, while the sum is 49.

The spelling of 644235584161 in words is "six hundred forty-four billion, two hundred thirty-five million, five hundred eighty-four thousand, one hundred sixty-one".