21221012166 has 16 divisors (see below), whose sum is σ = 42537835584. Its totient is φ = 7057702184.

The previous prime is 21221012119. The next prime is 21221012177. The reversal of 21221012166 is 66121012212.

It is a Curzon number.

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, 3989256 + ... + 3994571.

It is an arithmetic number, because the mean of its divisors is an integer number (2658614724).

Almost surely, 2^21221012166 is an apocalyptic number.

21221012166 is an abundant number, since it is smaller than the sum of its proper divisors (21316823418).

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

21221012166 is a wasteful number, since it uses less digits than its factorization.

21221012166 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7984275.

The product of its (nonzero) digits is 576, while the sum is 24.

Adding to 21221012166 its reverse (66121012212), we get a palindrome (87342024378).

The spelling of 21221012166 in words is "twenty-one billion, two hundred twenty-one million, twelve thousand, one hundred sixty-six".