21423536808 has 64 divisors (see below), whose sum is σ = 54911908800. Its totient is φ = 6961067520.

The previous prime is 21423536807. The next prime is 21423536831. The reversal of 21423536808 is 80863532412.

It is a self number, because there is not a number n which added to its sum of digits gives 21423536808.

It is not an unprimeable number, because it can be changed into a prime (21423536807) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1230210 + ... + 1247502.

It is an arithmetic number, because the mean of its divisors is an integer number (857998575).

Almost surely, 2^21423536808 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 21423536808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27455954400).

21423536808 is an abundant number, since it is smaller than the sum of its proper divisors (33488371992).

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

21423536808 is a wasteful number, since it uses less digits than its factorization.

21423536808 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18602 (or 18598 counting only the distinct ones).

The product of its (nonzero) digits is 276480, while the sum is 42.

The spelling of 21423536808 in words is "twenty-one billion, four hundred twenty-three million, five hundred thirty-six thousand, eight hundred eight".