21621343565166 has 32 divisors (see below), whose sum is σ = 43713606406176. Its totient is φ = 7128767760000.

The previous prime is 21621343565147. The next prime is 21621343565167. The reversal of 21621343565166 is 66156534312612.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21621343565167) 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, 16853745 + ... + 18091196.

It is an arithmetic number, because the mean of its divisors is an integer number (1366050200193).

Almost surely, 2^{21621343565166} is an apocalyptic number.

21621343565166 is an abundant number, since it is smaller than the sum of its proper divisors (22092262841010).

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

21621343565166 is a wasteful number, since it uses less digits than its factorization.

21621343565166 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34946068.

The product of its digits is 4665600, while the sum is 51.

Adding to 21621343565166 its reverse (66156534312612), we get a palindrome (87777877877778).

The spelling of 21621343565166 in words is "twenty-one trillion, six hundred twenty-one billion, three hundred forty-three million, five hundred sixty-five thousand, one hundred sixty-six".