20213131221 has 12 divisors (see below), whose sum is σ = 30138576000. Its totient is φ = 13040729640.

The previous prime is 20213131207. The next prime is 20213131231. The reversal of 20213131221 is 12213131202.

20213131221 is a `hidden beast` number, since 202 + 131 + 312 + 21 = 666.

It is not a de Polignac number, because 20213131221 - 2⁹ = 20213130709 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20213131194 and 20213131203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20213131231) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 36223971 + ... + 36224528.

It is an arithmetic number, because the mean of its divisors is an integer number (2511548000).

Almost surely, 2^20213131221 is an apocalyptic number.

It is an amenable number.

20213131221 is a deficient number, since it is larger than the sum of its proper divisors (9925444779).

20213131221 is a wasteful number, since it uses less digits than its factorization.

20213131221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72448536 (or 72448533 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

Adding to 20213131221 its reverse (12213131202), we get a palindrome (32426262423).

The spelling of 20213131221 in words is "twenty billion, two hundred thirteen million, one hundred thirty-one thousand, two hundred twenty-one".