20312131221 has 12 divisors (see below), whose sum is σ = 29395850848. Its totient is φ = 13515525864.

The previous prime is 20312131219. The next prime is 20312131261. The reversal of 20312131221 is 12213121302.

20312131221 is a `hidden beast` number, since 2 + 0 + 312 + 131 + 221 = 666.

It is not a de Polignac number, because 20312131221 - 2¹ = 20312131219 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20312131194 and 20312131203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20312131261) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2152945 + ... + 2162358.

Almost surely, 2^20312131221 is an apocalyptic number.

It is an amenable number.

20312131221 is a deficient number, since it is larger than the sum of its proper divisors (9083719627).

20312131221 is a wasteful number, since it uses less digits than its factorization.

20312131221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4315832 (or 4315829 counting only the distinct ones).

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

Adding to 20312131221 its reverse (12213121302), we get a palindrome (32525252523).

The spelling of 20312131221 in words is "twenty billion, three hundred twelve million, one hundred thirty-one thousand, two hundred twenty-one".