20805942816 has 144 divisors (see below), whose sum is σ = 61487112960. Its totient is φ = 6665541120.

The previous prime is 20805942803. The next prime is 20805942877. The reversal of 20805942816 is 61824950802.

20805942816 is a `hidden beast` number, since 20 + 8 + 0 + 594 + 28 + 16 = 666.

It is a tau number, because it is divible by the number of its divisors (144).

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1856911 + ... + 1868081.

It is an arithmetic number, because the mean of its divisors is an integer number (426993840).

Almost surely, 2^20805942816 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 20805942816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30743556480).

20805942816 is an abundant number, since it is smaller than the sum of its proper divisors (40681170144).

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

20805942816 is a wasteful number, since it uses less digits than its factorization.

20805942816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11439 (or 11428 counting only the distinct ones).

The product of its (nonzero) digits is 276480, while the sum is 45.

The spelling of 20805942816 in words is "twenty billion, eight hundred five million, nine hundred forty-two thousand, eight hundred sixteen".