20665049856 has 432 divisors, whose sum is σ = 65140088832. Its totient is φ = 5790597120.

The previous prime is 20665049851. The next prime is 20665049879. The reversal of 20665049856 is 65894056602.

It is a Harshad number since it is a multiple of its sum of digits (51).

It is a junction number, because it is equal to n+sod(n) for n = 20665049799 and 20665049808.

It is not an unprimeable number, because it can be changed into a prime (20665049851) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 162716865 + ... + 162716991.

Almost surely, 2^20665049856 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 20665049856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32570044416).

20665049856 is an abundant number, since it is smaller than the sum of its proper divisors (44475038976).

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

20665049856 is a wasteful number, since it uses less digits than its factorization.

20665049856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 288 (or 263 counting only the distinct ones).

The product of its (nonzero) digits is 3110400, while the sum is 51.

The spelling of 20665049856 in words is "twenty billion, six hundred sixty-five million, forty-nine thousand, eight hundred fifty-six".