20640688068 has 144 divisors (see below), whose sum is σ = 65819525184. Its totient is φ = 4948796160.

The previous prime is 20640688051. The next prime is 20640688093. The reversal of 20640688068 is 86088604602.

It is a happy number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 38655 + ... + 206822.

It is an arithmetic number, because the mean of its divisors is an integer number (457080036).

Almost surely, 2^20640688068 is an apocalyptic number.

20640688068 is a gapful number since it is divisible by the number (28) 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 20640688068, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32909762592).

20640688068 is an abundant number, since it is smaller than the sum of its proper divisors (45178837116).

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

20640688068 is a wasteful number, since it uses less digits than its factorization.

20640688068 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 245522 (or 245513 counting only the distinct ones).

The product of its (nonzero) digits is 884736, while the sum is 48.

The spelling of 20640688068 in words is "twenty billion, six hundred forty million, six hundred eighty-eight thousand, sixty-eight".