21135863872 has 56 divisors (see below), whose sum is σ = 44554241600. Its totient is φ = 9919812096.

The previous prime is 21135863867. The next prime is 21135863911. The reversal of 21135863872 is 27836853112.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 52813 + ... + 212275.

Almost surely, 2^21135863872 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 21135863872, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22277120800).

21135863872 is an abundant number, since it is smaller than the sum of its proper divisors (23418377728).

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

21135863872 is a wasteful number, since it uses less digits than its factorization.

21135863872 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 159603 (or 159593 counting only the distinct ones).

The product of its digits is 483840, while the sum is 46.

The spelling of 21135863872 in words is "twenty-one billion, one hundred thirty-five million, eight hundred sixty-three thousand, eight hundred seventy-two".