20211231221 has 8 divisors (see below), whose sum is σ = 20240996160. Its totient is φ = 20181486528.

The previous prime is 20211231217. The next prime is 20211231233. The reversal of 20211231221 is 12213211202.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20211231221 - 2² = 20211231217 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20211231221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20211231251) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4193405 + ... + 4198221.

It is an arithmetic number, because the mean of its divisors is an integer number (2530124520).

Almost surely, 2^20211231221 is an apocalyptic number.

It is an amenable number.

20211231221 is a deficient number, since it is larger than the sum of its proper divisors (29764939).

20211231221 is an equidigital number, since it uses as much as digits as its factorization.

20211231221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10123.

The product of its (nonzero) digits is 96, while the sum is 17.

Adding to 20211231221 its reverse (12213211202), we get a palindrome (32424442423).

The spelling of 20211231221 in words is "twenty billion, two hundred eleven million, two hundred thirty-one thousand, two hundred twenty-one".