21835139872 has 144 divisors (see below), whose sum is σ = 55842115392. Its totient is φ = 8183047680.

The previous prime is 21835139857. The next prime is 21835139873. The reversal of 21835139872 is 27893153812.

It is not an unprimeable number, because it can be changed into a prime (21835139873) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1040847 + ... + 1061617.

It is an arithmetic number, because the mean of its divisors is an integer number (387792468).

Almost surely, 2^21835139872 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 21835139872, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27921057696).

21835139872 is an abundant number, since it is smaller than the sum of its proper divisors (34006975520).

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

21835139872 is a wasteful number, since it uses less digits than its factorization.

21835139872 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20839 (or 20812 counting only the distinct ones).

The product of its digits is 725760, while the sum is 49.

The spelling of 21835139872 in words is "twenty-one billion, eight hundred thirty-five million, one hundred thirty-nine thousand, eight hundred seventy-two".