21013115008 has 64 divisors (see below), whose sum is σ = 43951147200. Its totient is φ = 9987867648.

The previous prime is 21013115003. The next prime is 21013115033. The reversal of 21013115008 is 80051131012.

It is a tau number, because it is divible by the number of its divisors (64).

It is a self number, because there is not a number n which added to its sum of digits gives 21013115008.

It is not an unprimeable number, because it can be changed into a prime (21013115003) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 457978 + ... + 501766.

It is an arithmetic number, because the mean of its divisors is an integer number (686736675).

Almost surely, 2^21013115008 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 21013115008, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21975573600).

21013115008 is an abundant number, since it is smaller than the sum of its proper divisors (22938032192).

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

21013115008 is a wasteful number, since it uses less digits than its factorization.

21013115008 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43989 (or 43977 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 22.

The spelling of 21013115008 in words is "twenty-one billion, thirteen million, one hundred fifteen thousand, eight".