20912173056 has 130 divisors (see below), whose sum is σ = 62471708552. Its totient is φ = 6970613760.

The previous prime is 20912173043. The next prime is 20912173067. The reversal of 20912173056 is 65037121902.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 20912173056.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 300261 + ... + 363291.

Almost surely, 2^20912173056 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 20912173056, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31235854276).

20912173056 is an abundant number, since it is smaller than the sum of its proper divisors (41559535496).

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

20912173056 is an frugal number, since it uses more digits than its factorization.

20912173056 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63067 (or 63036 counting only the distinct ones).

The product of its (nonzero) digits is 22680, while the sum is 36.

Adding to 20912173056 its reverse (65037121902), we get a palindrome (85949294958).

The spelling of 20912173056 in words is "twenty billion, nine hundred twelve million, one hundred seventy-three thousand, fifty-six".