20909492856 has 576 divisors, whose sum is σ = 74906208000. Its totient is φ = 5219665920.

The previous prime is 20909492843. The next prime is 20909492881. The reversal of 20909492856 is 65829490902.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 67232941 + ... + 67233251.

It is an arithmetic number, because the mean of its divisors is an integer number (130045500).

Almost surely, 2^20909492856 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 20909492856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37453104000).

20909492856 is an abundant number, since it is smaller than the sum of its proper divisors (53996715144).

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

20909492856 is a wasteful number, since it uses less digits than its factorization.

20909492856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 432 (or 418 counting only the distinct ones).

The product of its (nonzero) digits is 2799360, while the sum is 54.

The spelling of 20909492856 in words is "twenty billion, nine hundred nine million, four hundred ninety-two thousand, eight hundred fifty-six".