20644688172 has 12 divisors (see below), whose sum is σ = 48170939096. Its totient is φ = 6881562720.

The previous prime is 20644688159. The next prime is 20644688179. The reversal of 20644688172 is 27188644602.

It is a tau number, because it is divible by the number of its divisors (12).

It is not an unprimeable number, because it can be changed into a prime (20644688179) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 860195329 + ... + 860195352.

Almost surely, 2^20644688172 is an apocalyptic number.

It is an amenable number.

20644688172 is an abundant number, since it is smaller than the sum of its proper divisors (27526250924).

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

20644688172 is a wasteful number, since it uses less digits than its factorization.

20644688172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1720390688 (or 1720390686 counting only the distinct ones).

The product of its (nonzero) digits is 1032192, while the sum is 48.

The spelling of 20644688172 in words is "twenty billion, six hundred forty-four million, six hundred eighty-eight thousand, one hundred seventy-two".