20644390000 has 100 divisors (see below), whose sum is σ = 53827251016. Its totient is φ = 7622496000.

The previous prime is 20644389989. The next prime is 20644390009. The reversal of 20644390000 is 9344602.

It is a tau number, because it is divible by the number of its divisors (100).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20644390009) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 50599 + ... + 209401.

Almost surely, 2^20644390000 is an apocalyptic number.

20644390000 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20644390000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26913625508).

20644390000 is an abundant number, since it is smaller than the sum of its proper divisors (33182861016).

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

20644390000 is a wasteful number, since it uses less digits than its factorization.

20644390000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 158844 (or 158823 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 28.

The spelling of 20644390000 in words is "twenty billion, six hundred forty-four million, three hundred ninety thousand".