21187129216 has 128 divisors (see below), whose sum is σ = 48598185600. Its totient is φ = 9099417600.

The previous prime is 21187129199. The next prime is 21187129237. The reversal of 21187129216 is 61292178112.

It is a tau number, because it is divible by the number of its divisors (128).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13134426 + ... + 13136038.

It is an arithmetic number, because the mean of its divisors is an integer number (379673325).

Almost surely, 2^21187129216 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 21187129216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24299092800).

21187129216 is an abundant number, since it is smaller than the sum of its proper divisors (27411056384).

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

21187129216 is a wasteful number, since it uses less digits than its factorization.

21187129216 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2148 (or 2136 counting only the distinct ones).

The product of its digits is 24192, while the sum is 40.

The spelling of 21187129216 in words is "twenty-one billion, one hundred eighty-seven million, one hundred twenty-nine thousand, two hundred sixteen".