20130121021 has 2 divisors, whose sum is σ = 20130121022. Its totient is φ = 20130121020.

The previous prime is 20130120961. The next prime is 20130121117. The reversal of 20130121021 is 12012103102.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20127096900 + 3024121 = 141870^2 + 1739^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20130121021 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20130120992 and 20130121010.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20130122021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10065060510 + 10065060511.

It is an arithmetic number, because the mean of its divisors is an integer number (10065060511).

Almost surely, 2^20130121021 is an apocalyptic number.

It is an amenable number.

20130121021 is a deficient number, since it is larger than the sum of its proper divisors (1).

20130121021 is an equidigital number, since it uses as much as digits as its factorization.

20130121021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 24, while the sum is 13.

Adding to 20130121021 its reverse (12012103102), we get a palindrome (32142224123).

The spelling of 20130121021 in words is "twenty billion, one hundred thirty million, one hundred twenty-one thousand, twenty-one".