20938409856 has 768 divisors, whose sum is σ = 81265766400. Its totient is φ = 5016453120.

The previous prime is 20938409803. The next prime is 20938409867. The reversal of 20938409856 is 65890483902.

20938409856 is a `hidden beast` number, since 209 + 384 + 0 + 9 + 8 + 56 = 666.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 55246275 + ... + 55246653.

It is an arithmetic number, because the mean of its divisors is an integer number (105814800).

Almost surely, 2^20938409856 is an apocalyptic number.

20938409856 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20938409856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40632883200).

20938409856 is an abundant number, since it is smaller than the sum of its proper divisors (60327356544).

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

20938409856 is a wasteful number, since it uses less digits than its factorization.

20938409856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 467 (or 452 counting only the distinct ones).

The product of its (nonzero) digits is 3732480, while the sum is 54.

The spelling of 20938409856 in words is "twenty billion, nine hundred thirty-eight million, four hundred nine thousand, eight hundred fifty-six".