20421213121 has 2 divisors, whose sum is σ = 20421213122. Its totient is φ = 20421213120.

The previous prime is 20421213103. The next prime is 20421213139. The reversal of 20421213121 is 12131212402.

It is a balanced prime because it is at equal distance from previous prime (20421213103) and next prime (20421213139).

It can be written as a sum of positive squares in only one way, i.e., 17838540721 + 2582672400 = 133561^2 + 50820^2 .

It is a cyclic number.

It is not a de Polignac number, because 20421213121 - 2¹⁷ = 20421082049 is a prime.

It is not a weakly prime, because it can be changed into another prime (20421213101) 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 as a sum of consecutive naturals, namely, 10210606560 + 10210606561.

It is an arithmetic number, because the mean of its divisors is an integer number (10210606561).

Almost surely, 2^20421213121 is an apocalyptic number.

It is an amenable number.

20421213121 is a deficient number, since it is larger than the sum of its proper divisors (1).

20421213121 is an equidigital number, since it uses as much as digits as its factorization.

20421213121 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 192, while the sum is 19.

Adding to 20421213121 its reverse (12131212402), we get a palindrome (32552425523).

The spelling of 20421213121 in words is "twenty billion, four hundred twenty-one million, two hundred thirteen thousand, one hundred twenty-one".