20013131221 has 6 divisors (see below), whose sum is σ = 21259624130. Its totient is φ = 18835887936.

The previous prime is 20013131213. The next prime is 20013131231. The reversal of 20013131221 is 12213131002.

It can be written as a sum of positive squares in 3 ways, for example, as 6327407025 + 13685724196 = 79545^2 + 116986^2 .

It is not a de Polignac number, because 20013131221 - 2³ = 20013131213 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20013131195 and 20013131204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20013131231) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 34624506 + ... + 34625083.

Almost surely, 2^20013131221 is an apocalyptic number.

It is an amenable number.

20013131221 is a deficient number, since it is larger than the sum of its proper divisors (1246492909).

20013131221 is an equidigital number, since it uses as much as digits as its factorization.

20013131221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 69249623 (or 69249606 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 16.

Adding to 20013131221 its reverse (12213131002), we get a palindrome (32226262223).

The spelling of 20013131221 in words is "twenty billion, thirteen million, one hundred thirty-one thousand, two hundred twenty-one".