20917337856 has 144 divisors (see below), whose sum is σ = 59189792256. Its totient is φ = 6543167488.

The previous prime is 20917337813. The next prime is 20917337911. The reversal of 20917337856 is 65873371902.

It is a junction number, because it is equal to n+sod(n) for n = 20917337799 and 20917337808.

It is a congruent number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 925021 + ... + 947363.

It is an arithmetic number, because the mean of its divisors is an integer number (411040224).

Almost surely, 2^20917337856 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 20917337856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29594896128).

20917337856 is an abundant number, since it is smaller than the sum of its proper divisors (38272454400).

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

20917337856 is a wasteful number, since it uses less digits than its factorization.

20917337856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22438 (or 22424 counting only the distinct ones).

The product of its (nonzero) digits is 1905120, while the sum is 51.

The spelling of 20917337856 in words is "twenty billion, nine hundred seventeen million, three hundred thirty-seven thousand, eight hundred fifty-six".