21115329664 has 128 divisors (see below), whose sum is σ = 51125256000. Its totient is φ = 8553861120.

The previous prime is 21115329661. The next prime is 21115329673. The reversal of 21115329664 is 46692351112.

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

It is not an unprimeable number, because it can be changed into a prime (21115329661) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 510927 + ... + 550705.

Almost surely, 2^21115329664 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 21115329664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25562628000).

21115329664 is an abundant number, since it is smaller than the sum of its proper divisors (30009926336).

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

21115329664 is a wasteful number, since it uses less digits than its factorization.

21115329664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39846 (or 39834 counting only the distinct ones).

The product of its digits is 77760, while the sum is 40.

The spelling of 21115329664 in words is "twenty-one billion, one hundred fifteen million, three hundred twenty-nine thousand, six hundred sixty-four".