20668265856 has 576 divisors, whose sum is σ = 73139189760. Its totient is φ = 5791564800.

The previous prime is 20668265801. The next prime is 20668265861. The reversal of 20668265856 is 65856286602.

It is a tau number, because it is divible by the number of its divisors (576).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 108210721 + ... + 108210911.

It is an arithmetic number, because the mean of its divisors is an integer number (126977760).

Almost surely, 2^20668265856 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20668265856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36569594880).

20668265856 is an abundant number, since it is smaller than the sum of its proper divisors (52470923904).

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

20668265856 is an equidigital number, since it uses as much as digits as its factorization.

20668265856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 305 (or 274 counting only the distinct ones).

The product of its (nonzero) digits is 8294400, while the sum is 54.

The spelling of 20668265856 in words is "twenty billion, six hundred sixty-eight million, two hundred sixty-five thousand, eight hundred fifty-six".