21115829664 has 144 divisors (see below), whose sum is σ = 63441312480. Its totient is φ = 6643607040.

The previous prime is 21115829641. The next prime is 21115829677. The reversal of 21115829664 is 46692851112.

21115829664 is a `hidden beast` number, since 2 + 1 + 1 + 1 + 582 + 9 + 6 + 64 = 666.

It is a tau number, because it is divible by the number of its divisors (144).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1508779 + ... + 1522709.

It is an arithmetic number, because the mean of its divisors is an integer number (440564670).

Almost surely, 2^21115829664 is an apocalyptic number.

21115829664 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21115829664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31720656240).

21115829664 is an abundant number, since it is smaller than the sum of its proper divisors (42325482816).

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

21115829664 is a wasteful number, since it uses less digits than its factorization.

21115829664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14243 (or 14232 counting only the distinct ones).

The product of its digits is 207360, while the sum is 45.

The spelling of 21115829664 in words is "twenty-one billion, one hundred fifteen million, eight hundred twenty-nine thousand, six hundred sixty-four".