21808665792 has 84 divisors (see below), whose sum is σ = 62779275000. Its totient is φ = 7238310912.

The previous prime is 21808665751. The next prime is 21808665817. The reversal of 21808665792 is 29756680812.

21808665792 is a `hidden beast` number, since 2 + 1 + 8 + 0 + 8 + 66 + 579 + 2 = 666.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 52959 + ... + 215457.

Almost surely, 2^21808665792 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 21808665792, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31389637500).

21808665792 is an abundant number, since it is smaller than the sum of its proper divisors (40970609208).

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

21808665792 is a wasteful number, since it uses less digits than its factorization.

21808665792 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 162750 (or 162737 counting only the distinct ones).

The product of its (nonzero) digits is 2903040, while the sum is 54.

The spelling of 21808665792 in words is "twenty-one billion, eight hundred eight million, six hundred sixty-five thousand, seven hundred ninety-two".