21210133566 has 16 divisors (see below), whose sum is σ = 42422302224. Its totient is φ = 7069705344.

The previous prime is 21210133543. The next prime is 21210133579. The reversal of 21210133566 is 66533101212.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 73396 + ... + 218648.

It is an arithmetic number, because the mean of its divisors is an integer number (2651393889).

Almost surely, 2^21210133566 is an apocalyptic number.

21210133566 is an abundant number, since it is smaller than the sum of its proper divisors (21212168658).

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

21210133566 is a wasteful number, since it uses less digits than its factorization.

21210133566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 169595.

The product of its (nonzero) digits is 6480, while the sum is 30.

Adding to 21210133566 its reverse (66533101212), we get a palindrome (87743234778).

The spelling of 21210133566 in words is "twenty-one billion, two hundred ten million, one hundred thirty-three thousand, five hundred sixty-six".