21109156864 has 132 divisors (see below), whose sum is σ = 45938364600. Its totient is φ = 9667952640.

The previous prime is 21109156847. The next prime is 21109156907. The reversal of 21109156864 is 46865190112.

It is a self number, because there is not a number n which added to its sum of digits gives 21109156864.

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, 18696652 + ... + 18697780.

Almost surely, 2^21109156864 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 21109156864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22969182300).

21109156864 is an abundant number, since it is smaller than the sum of its proper divisors (24829207736).

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

21109156864 is a wasteful number, since it uses less digits than its factorization.

21109156864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1230 (or 1181 counting only the distinct ones).

The product of its (nonzero) digits is 103680, while the sum is 43.

The spelling of 21109156864 in words is "twenty-one billion, one hundred nine million, one hundred fifty-six thousand, eight hundred sixty-four".