21134205666 has 96 divisors (see below), whose sum is σ = 56648177280. Its totient is φ = 5720499936.

The previous prime is 21134205649. The next prime is 21134205667. The reversal of 21134205666 is 66650243112.

21134205666 is digitally balanced in base 5, because in such base it contains all the possibile digits an equal number of times.

It is a self number, because there is not a number n which added to its sum of digits gives 21134205666.

It is not an unprimeable number, because it can be changed into a prime (21134205667) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 59020 + ... + 213896.

It is an arithmetic number, because the mean of its divisors is an integer number (590085180).

Almost surely, 2^21134205666 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21134205666, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28324088640).

21134205666 is an abundant number, since it is smaller than the sum of its proper divisors (35513971614).

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

21134205666 is a wasteful number, since it uses less digits than its factorization.

21134205666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 154933 (or 154908 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 36.

Adding to 21134205666 its reverse (66650243112), we get a palindrome (87784448778).

The spelling of 21134205666 in words is "twenty-one billion, one hundred thirty-four million, two hundred five thousand, six hundred sixty-six".