20213231021 has 2 divisors, whose sum is σ = 20213231022. Its totient is φ = 20213231020.

The previous prime is 20213230991. The next prime is 20213231039. The reversal of 20213231021 is 12013231202.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19747275625 + 465955396 = 140525^2 + 21586^2 .

It is a cyclic number.

It is not a de Polignac number, because 20213231021 - 2¹⁰ = 20213229997 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20213231821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10106615510 + 10106615511.

It is an arithmetic number, because the mean of its divisors is an integer number (10106615511).

Almost surely, 2^20213231021 is an apocalyptic number.

It is an amenable number.

20213231021 is a deficient number, since it is larger than the sum of its proper divisors (1).

20213231021 is an equidigital number, since it uses as much as digits as its factorization.

20213231021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 144, while the sum is 17.

Adding to 20213231021 its reverse (12013231202), we get a palindrome (32226462223).

The spelling of 20213231021 in words is "twenty billion, two hundred thirteen million, two hundred thirty-one thousand, twenty-one".