20513400121 has 2 divisors, whose sum is σ = 20513400122. Its totient is φ = 20513400120.

The previous prime is 20513400119. The next prime is 20513400139. The reversal of 20513400121 is 12100431502.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16094474496 + 4418925625 = 126864^2 + 66475^2 .

It is a cyclic number.

It is not a de Polignac number, because 20513400121 - 2¹ = 20513400119 is a prime.

Together with 20513400119, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (20513400161) 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, 10256700060 + 10256700061.

It is an arithmetic number, because the mean of its divisors is an integer number (10256700061).

Almost surely, 2^20513400121 is an apocalyptic number.

It is an amenable number.

20513400121 is a deficient number, since it is larger than the sum of its proper divisors (1).

20513400121 is an equidigital number, since it uses as much as digits as its factorization.

20513400121 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 240, while the sum is 19.

Adding to 20513400121 its reverse (12100431502), we get a palindrome (32613831623).

The spelling of 20513400121 in words is "twenty billion, five hundred thirteen million, four hundred thousand, one hundred twenty-one".