21135215166 has 16 divisors (see below), whose sum is σ = 45522002064. Its totient is φ = 6503143104.

The previous prime is 21135215161. The next prime is 21135215183. The reversal of 21135215166 is 66151253112.

It is a super-2 number, since 2×21135215166² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21135215161) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 135482071 + ... + 135482226.

It is an arithmetic number, because the mean of its divisors is an integer number (2845125129).

Almost surely, 2^21135215166 is an apocalyptic number.

21135215166 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

21135215166 is an abundant number, since it is smaller than the sum of its proper divisors (24386786898).

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

21135215166 is a wasteful number, since it uses less digits than its factorization.

21135215166 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 270964315.

The product of its digits is 10800, while the sum is 33.

Adding to 21135215166 its reverse (66151253112), we get a palindrome (87286468278).

The spelling of 21135215166 in words is "twenty-one billion, one hundred thirty-five million, two hundred fifteen thousand, one hundred sixty-six".