21216210631166 has 16 divisors (see below), whose sum is σ = 32106584618064. Its totient is φ = 10514019487104.

The previous prime is 21216210631157. The next prime is 21216210631171. The reversal of 21216210631166 is 66113601261212.

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, 10799921 + ... + 12612323.

It is an arithmetic number, because the mean of its divisors is an integer number (2006661538629).

Almost surely, 2^{21216210631166} is an apocalyptic number.

21216210631166 is a deficient number, since it is larger than the sum of its proper divisors (10890373986898).

21216210631166 is a wasteful number, since it uses less digits than its factorization.

21216210631166 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1864315.

The product of its (nonzero) digits is 31104, while the sum is 38.

Adding to 21216210631166 its reverse (66113601261212), we get a palindrome (87329811892378).

The spelling of 21216210631166 in words is "twenty-one trillion, two hundred sixteen billion, two hundred ten million, six hundred thirty-one thousand, one hundred sixty-six".