20644911840 has 384 divisors, whose sum is σ = 76082872320. Its totient is φ = 4608165888.

The previous prime is 20644911827. The next prime is 20644911841. The reversal of 20644911840 is 4811944602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20644911841) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 44207287 + ... + 44207753.

It is an arithmetic number, because the mean of its divisors is an integer number (198132480).

Almost surely, 2^20644911840 is an apocalyptic number.

20644911840 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 20644911840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38041436160).

20644911840 is an abundant number, since it is smaller than the sum of its proper divisors (55437960480).

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

20644911840 is a wasteful number, since it uses less digits than its factorization.

20644911840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 774 (or 766 counting only the distinct ones).

The product of its (nonzero) digits is 55296, while the sum is 39.

The spelling of 20644911840 in words is "twenty billion, six hundred forty-four million, nine hundred eleven thousand, eight hundred forty".