20665808128 has 72 divisors (see below), whose sum is σ = 49625213120. Its totient is φ = 8390615040.

The previous prime is 20665808123. The next prime is 20665808143. The reversal of 20665808128 is 82180856602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20665808123) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 269433 + ... + 337528.

Almost surely, 2^20665808128 is an apocalyptic number.

20665808128 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

20665808128 is an abundant number, since it is smaller than the sum of its proper divisors (28959404992).

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

20665808128 is an equidigital number, since it uses as much as digits as its factorization.

20665808128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 607003 (or 606989 counting only the distinct ones).

The product of its (nonzero) digits is 368640, while the sum is 46.

The spelling of 20665808128 in words is "twenty billion, six hundred sixty-five million, eight hundred eight thousand, one hundred twenty-eight".